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We present measurements of single electron tunneling through a quantum dot (QD) using a quantum point contact as charge detector. The counting statistics for varying symmetry of the QD system is examined from a very large statistical basis. We extract high order cumulants describing the distribution and observe prominent oscillations when varying the symmetry. We compare this behavior to the observed oscillation in time dependence and show that the variation in both system variables lead to the same kind of oscillating response. [ABSTRACT FROM AUTHOR]

We examine the dynamical properties of resonant tunneling through single InAs quantum dots by measuring the shot noise of the current. We observe an approximately linear voltage dependence of both the shot noise, characterized by the Fano factor, and the tunneling current itself. We ascribe this to the three-dimensional density of states of the emitter and collector and are able to model the voltage dependence using a master equation approach. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

Quantum dots are quasi zero-dimensional systems in semiconductors and they represent promising candidates for future applications in quantum information processing. Their electronic properties are influenced by interaction and correlation effects, which are not clearly revealed in simple transport experiments. Shot noise measurements allow to investigate such interaction and correlation effects in detail and can lead to astonishing results. We studied shot noise in electrical transport through single and coupled quantum dots and found for single quantum dots suppressed shot noise in respect to Poissonian noise as, e.g. is assumed in the recently developed technique of spin noise spectroscopy. Whereas the suppressed shot noise in single dots weakly coupled to the leads can be explained in simple models using emitter and collector tunnelling rates, for strong coupling an additional suppression is observed where interaction effects have to be taken into account. In recent measurements on coupled quantum dots an astonishing enhancement of shot noise, i.e. super-Poissonian noise, was found being in stark contrast to the suppression of shot noise found for single quantum dots. This enhancement of shot noise cannot be understood in a single-particle picture neglecting interactions. An enhanced shot noise could result from a coupling to other stacks of coupled quantum dots or from interaction and coherence effects within one stack. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]