  We consider the generation of entropy when particle pairs are created at a
cosmological level. Making a reduction via the particle number basis, we
compute the classical limit for the entropy generation due to the evolution of
the matter field fluctuations (squeeze transformation), obtaining that it is
linear in the squeeze parameter for a general class of initial states. We also
discuss the dependence of the generated entropy on the coarse graining
criteria.

General Relativity and Quantum Cosmology