  We study a voltage biased Josephson junction coupled to two resonators of
incommensurate frequencies. Using a density approach to analyze the cavity
fields and an input-output description to analyze the emitted photonic fluxes
and their correlation functions, we have shown, both for infinite and finite
bandwidth detectors, that the emitted radiation is non-classical in the sense
that the correlators violates Cauchy-Schwarz inequalities. We have also studied
the time dependence of the photonic correlations and showed that their
line-width becomes narrower with the increase of the emission rate approaching
from below the threshold limit.
