Analog simulations of early universe pre-heating and the back-reaction effect

Abstract

We theoretically propose a ring-shaped, two-dimensional atomic Bose-Einstein condensate as analog model to investigate back-reaction effects during the pre-heating of the early universe. We study the out-of-equilibrium dynamics by which the inflaton field decays by parametrically exciting the vacuum fluctuations that initially populate the matter fields. By working at the level of the truncated Wigner approximation, our numerical simulations show how a signature of back-reaction beyond the semiclassical level is encoded in the effective friction experienced by the analog of the inflaton field, as well as in the spatial de-phasing of its oscillations and in the entanglement between the inflaton and matter fields degrees-of-freedoms.