THE COHERENCE OF PRIMORDIAL FLUCTUATIONS PRODUCED DURING INFLATION

The behaviour of quantum metric perturbations produced during inflatio n is considered at the stage after the second Hubble radius crossing. It is shown that the classical correlation between amplitude and momen tum of a perturbation mode, previously shown to emerge in the course o f an effective quantum-to-classical transition, is maintained for a. s ufficiently long time, and we present the explicit form it takes using the Wigner function. We further show with a simple diffraction experi ment that quantum interference, non-expressible in terms of a classica l stochastic description of the perturbations, is essentially suppress ed. Rescattering of the perturbations leads to a comparatively slow de cay of this correlation and to a complete stochastization of the syste m.