  It has been shown beyond reasonable doubt that the majority (about 95%) of
the total energy budget of the universe is given by the dark components, namely
Dark Matter and Dark Energy. What constitutes these components remains to be
satisfactorily understood however, despite a number of promising candidates. An
associated conundrum is that of the coincidence, i.e. the question as to why
the Dark Matter and Dark Energy densities are of the same order of magnitude at
the present epoch, after evolving over the entire expansion history of the
universe. In an attempt to address these, we consider a quantum potential
resulting from a quantum corrected Raychaudhuri/Friedmann equation in presence
of a cosmic fluid, which is presumed to be a Bose-Einstein condensate (BEC) of
ultralight bosons. For a suitable and physically motivated macroscopic ground
state wavefunction of the BEC, we show that a unified picture of the cosmic
dark sector can indeed emerge, thus resolving the issue of the coincidence. The
effective Dark energy component turns out to be a cosmological constant, by
virtue of a residual homogeneous term in the quantum potential. Furthermore,
comparison with the observational data gives an estimate of the mass of the
constituent bosons in the BEC, which is well within the bounds predicted from
other considerations.
