  We clarify the controversy over the coherent-state (CS) versus the
number-state (NS) pictures in quantum optics. The NS picture is equivalent to
the CS picture, as long as the phases $\phi$ in the laser fields are randomly
distributed, as M{\o}lmer argues [\pra {\bf 55}, 3195 (1997)]. However, the
claim by Rudolph and Sanders [Phys. Rev. Lett. {\bf 87}, 077903 (2001)] has a
few gaps. First, they make an assumption that is not necessarily true in the
calculation of a density operator involved with a two-mode squeezed state. We
show that there exists entanglement in the density operator without defying the
assumption that phases are randomly distributed. Moreover, using a concept of
picture-invariance, we argue that it is not that criteria for quantum
teleportation are not satisfied. We discuss an analogy between the controversy
on the CS versus NS pictures to that on the heliocentric versus geocentric
pictures.
