Tunable super-Poissonian noise and negative differential conductance in two coherent strongly coupled quantum dots

Abstract

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., ϵ L > ϵ R , 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 ϵ L < ϵ R 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.