  The formation of frozen classical perturbations from vacuum quantum
fluctuations during inflation is described as a unitary quantum process with
apparent "decoherence" caused by the expanding spacetime. It is argued that the
maximum observable information content per comoving volume in classical modes
is subject to the covariant entropy bound at the time those modes decohere,
leading to a new quantitative bound on the information contained in frozen
field modes in phase space. This bound implies holographic correlations of
large-scale cosmological perturbations that may be observable.
