  We apply concepts from the quantum measurement theory to obtain some
cosmological neutrino background (C$\nu$B) properties and discuss their
relevance in defining theoretical bounds on cosmological neutrino energy
density. Describing three neutrino generations as a composite quantum system
through the generalized theory of quantum measurement provides us with the
probabilistic correlation between observable energies and neutrino flavor
eigenstates. By observing that flavor-averaged and flavor-weighted energies are
the quantum observables respectively generated by selective and non-selective
quantum measurement schemes, it is possible to identify the constraints on the
effective mass value expression that determines the neutrino contribution to
the energy density of the cosmic inventory. Our results agree with the quantum
mechanics viewpoint that asserts that the cosmological neutrino energy density
is obtained from a coherent sum of mass eigenstate energies, for normal and
inverted mass hierarchies.
