Large Squeezing Behavior of Cosmological Entropy Generation
  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. 
M. Kruczenski, L.E. Oxman and M. Zaldarriaga