Entanglement in model-independent cosmological scenario

We propose a model-independent approach to study entanglement creation due to the dynamics between two asymptotic quantum regimes in the framework of homogeneous and isotropic universe. We realize it by Pade expansion to reconstruct the functional form of scale factor, rather than postulating it a priori. This amounts to fix the Pade approximants constraining the free parameters in terms of current cosmic observations. Assuming fermions, we solve the Dirac equation for massive particles and we investigate entanglement entropy in terms of modes k and mass m. We consider two rational approximations of (1, 1) and (1, 2) orders, which turn out to be the most suitable choices for guaranteeing cosmic bounds. Our results show qualitative agreement with those known in literature and arising from toy models, but with sensible quantitative discrepancies. Moreover, our outcomes are model-independent reconstructions which show that any higher orders departing from (1, 1) do not significantly modify particle-antiparticle production (hence entanglement), if cosmic bounds are taken into account.