Bimodal Counting Statistics in Single Electron Tunneling through a Quantum Dot

TL;DR

This paper investigates the full counting statistics of single electron tunneling through a quantum dot, revealing bimodal distributions and super-Poissonian behavior linked to excited states and slow configuration switching.

Contribution

It demonstrates the measurement of counting statistics in quantum dots and uncovers bimodal distributions related to electron state switching.

Findings

Observation of super-Poissonian statistics at certain bias voltages

Identification of bimodal counting distributions

Linking bimodal behavior to slow switching between electron configurations

Abstract

We explore the full counting statistics of single electron tunneling through a quantum dot using a quantum point contact as non-invasive high bandwidth charge detector. The distribution of counted tunneling events is measured as a function of gate and source-drain-voltage for several consecutive electron numbers on the quantum dot. For certain configurations we observe super-Poissonian statistics for bias voltages at which excited states become accessible. The associated counting distributions interestingly show a bimodal characteristic. Analyzing the time dependence of the number of electron counts we relate this to a slow switching between different electron configurations on the quantum dot.