The CνB energy density through the quantum measurement theory

► Quantum measurement concepts are introduced for defining the CνB energy density. ► Quantum observables related to flavor associated energy densities are investigated. ► Ambiguities in defining observable energies are overcome by density matrix properties. ► CνB energy density is obtained through a coherent sum of mass eigenstate energies. ► A maximal flavor statistical mixing recovers the single particle QM results for CνB.