Frequency-dependent counting statistics in interacting nanoscale conductors

We present a formalism to calculate finite-frequency current correlations in interacting nanoscopic conductors. We work within the n-resolved density matrix approach and obtain a multitime cumulant generating function that provides the fluctuation statistics solely from the spectral decomposition of the Liouvillian. We apply the method to the frequency-dependent third cumulant of the current through a single resonant level and through a double quantum dot. Our results, which show that deviations from Poissonian behavior strongly depend on frequency, demonstrate the importance of finite-frequency higher-order cumulants in fully characterizing transport.