Waiting time distribution and the zero-frequency full counting statistics ofunidirectional electron transport through a double quantum dot moleculeattached to spin-polarized leads are analyzed using the quantum masterequation. The waiting time distribution exhibits a non-trivial dependence onthe value of the exchange coupling between the dots and the gradient of theapplied magnetic field, which reveals the oscillations between the spin statesof the molecule. The zero-frequency full counting statistics, on the otherhand, is independent of the aforementioned quantities, thus giving no insightinto the internal dynamics. The fact that the waiting time distribution and thezero-frequency full counting statistics give a non-equivalent information isassociated with two factors. Firstly, it can be explained by the sensitivity todifferent timescales of the dynamics of the system. Secondly, it is associatedwith the presence of the correlation between subsequent waiting times, whichmakes the renewal theory, relating the full counting statistics and the waitingtime distribution, not longer applicable. The study highlights the particularusefulness of the waiting time distribution for the analysis of the internaldynamics of mesoscopic systems.
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