  Distributions of electron waiting times have been measured in several recent
experiments and have been shown to provide complementary information compared
to what can be learned from the electric current fluctuations. Existing
theories, however, are restricted to either weakly coupled nanostructures or
phase-coherent transport in mesoscopic conductors. Here, we consider an
interacting quantum dot and develop a real-time diagrammatic theory of waiting
time distributions that can treat the interesting regime, in which both
interaction effects and higher-order tunneling processes are important.
Specifically, we find that our quantum-mechanical theory captures higher-order
tunneling processes at low temperatures, which are not included in a classical
description, and which dramatically affect the waiting times by allowing fast
tunneling processes inside the Coulomb blockade region. Our work paves the way
for systematic investigations of temporal fluctuations in interacting quantum
systems, for example close to a Kondo resonance or in a Luttinger liquid.
