  The distribution of waiting times between successive tunneling events is an
already established method to characterize current fluctuations in mesoscopic
systems. Here, I investigate mechanisms generating correlations between
subsequent waiting times in two model systems, a pair of capacitively coupled
quantum dots and a single-level dot attached to spin-polarized leads. Waiting
time correlations are shown to give an insight into the internal dynamics of
the system, for example they allow distinction between different mechanisms of
the noise enhancement. Moreover, the presence of correlations breaks the
validity of the renewal theory. This increases the number of independent
cumulants of current fluctuation statistics, thus providing additional sources
of information about the transport mechanism. I also propose a method for
inferring the presence of waiting time correlations based on low-order current
correlation functions. This method gives a way to extend the analysis of
nonrenewal current fluctuations to the systems for which single-electron
counting is not experimentally feasible. The experimental relevance of the
findings is also discussed, for example reanalysis of previous results
concerning transport in quantum dots is suggested.
