Tunable electron counting statistics in a quantum dot at thermal equilibrium

Tunneling of individual electrons into and out of a GaAs quantum dot is measured in real time by an adjacent charge detector. By controllably increasing the tunneling rate at thermal equilibrium, the full-counting statistics of these tunneling events shows a sub- to super-Poissonian transition, accompanied by a sign reversal of its third statistical moment. These anomalies are believed to be caused by electron tunneling through the singlet-triplet states of an elongated double dot, confirmed by a self-consistent Poisson-Schr\"odinger wave-function calculation.