  We derive the symmetrized current-noise spectrum of a quantum dot, which is
weakly tunnel-coupled to an electron reservoir and driven by a slow
time-dependent gate voltage. This setup can be operated as an on-demand emitter
of single electrons into a mesoscopic conductor. By extending a real-time
diagrammatic technique which is perturbative in the tunnel coupling, we obtain
the time-resolved finite-frequency noise as well as its decomposition into
noise harmonics in the presence of both strong Coulomb interaction and slow
time-dependent driving. We investigate the noise over a large range of
frequencies and point out where the interplay of Coulomb interaction and
driving leads to unique signatures in finite-frequency noise spectra, in
particular in the first harmonic. Besides that, we employ the first noise
harmonic as a spectroscopic tool to access individual fluctuation processes. We
discuss how the inverse noise frequency sets a time scale for fluctuations,
which competes with time scales of the quantum-dot relaxation dynamics as well
as the driving.
