  We use the language of squeezed states to give a systematic description of
two issues in cosmological particle creation: a) Dependence of particle
creation on the initial state specified. We consider in particular the number
state, the coherent and the squeezed state. b) The relation of spontaneous and
stimulated particle creation and their dependence on the initial state. We also
present results for the fluctuations in particle number in anticipation of its
relevance to defining noise in quantum fields and the vacuum susceptibility of
spacetime.
