  We discuss time-dependent factorial cumulants in interacting nano-scale
systems. Recent theoretical work has shown that the full counting statistics of
non-interacting electrons in a two-terminal conductor is always generalized
binomial and the zeros of the generating function are consequently real and
negative. However, as interactions are introduced in the transport, the zeros
of the generating function may become complex. This has measurable
consequences: With the zeros of the generating function moving away from the
real-axis, the high-order factorial cumulants of the transport become
oscillatory functions of time. Here we demonstrate this phenomenon on a model
of charge transport through coherently coupled quantum dots attached to
voltage-biased electrodes. Without interactions, the factorial cumulants are
monotonic functions of the observation time. In contrast, as interactions are
introduced, the factorial cumulants oscillate strongly as functions of time. We
comment on possible measurements of oscillating factorial cumulants and outline
several avenues for further investigations.
