  The role of the spatiotemporal degrees of freedom in the preparation and
observation of squeezed photonic states, produced by parametric
down-conversion, is investigated. The analysis is done with the aid of a
functional approach under the semi-classical approximation and the thin-crystal
approximation. It is found that the squeezed state loses its minimum
uncertainty property as the efficiency of down-conversion is increased, in a
way that depends on the conditions of the homodyne measurements with which the
amount of squeezing is determined.
