  Coherent states are normally used to describe the state of a laser field in
experiments that generate and detect squeezed states of light. Nevertheless,
since the laser field absolute phase is unknown, its quantum state can be
described by a statistical mixture of coherent states with random phases, which
is equivalent to a statistical mixture of Fock states. Here we describe
single-mode squeezed vacuum experiments using this mixed quantum state for the
laser field. Representing the laser state in the Fock basis, we predict the
usual experimental results without using the squeezing concept in the analysis
and concluding that no squeezed state is generated in the experiments. We
provide a general physical explanation for the noise reduction in the
experiments in terms of a better definition of the relative phase between the
signal and local oscillator fields. This explanation is valid in any
description of the laser field (in terms of coherent or Fock states), thus
providing a deeper understanding of the phenomenon.
