Tunable super-Poissonian noise and negative differential conductance in two coherent strongly coupled quantum dots
Department of Physics and Optoelectronics, Taiyuan University of
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Received in final form: 5 August 2012
Published online: 1 October 2012
The full counting statistics of electron transport through two coherent strongly serially coupled quantum dots (QDs) is theoretically studied based on an efficient particle-number-resolved master equation. When the coupling of the double-QD system with the incident-electrode is stronger than that with the outgoing-electrode, it is demonstrated that the super-Poissonian noise bias voltage range, which originates from the so-called dynamical channel blockade mechanism, depends sensitively on the types of energy-level detuning, which means that the super-Poissonian noise bias voltage range can be controlled by energy-level detuning and can be used to reveal the internal energy level structure of the considered double-QD system. For the on-site energy of the left QD coupled to incident-electrode is larger than that of the right QD coupled to out-electrode, i.e., ϵL > ϵR, a strong negative differential conductance (NDC) is observed in a certain energy-level detuning range and this level detuning range depends on the interdot Coulomb interaction, which suggests a tunable NDC device; whereas for ϵL < ϵR the magnitude of NDC is relatively very weak, and the corresponding shot noise is not always enhanced and even decreased at appropriate energy-level detuning. Moreover, the super-Poissonian behaviors of skewness and kurtosis are found to be more sensitive to the effective competition between the fast-and-slow transport channels than shot noise.
Key words: Mesoscopic and Nanoscale Systems
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag, 2012