Analogue Cosmological Particle Creation: Quantum Correlations in Expanding Bose Einstein Condensates

We investigate the structure of quantum correlations in an expanding Bose-Einstein condensate (BEC) through the analogue gravity framework. We consider both a 3 + 1 isotropically expanding BEC as well as the experimentally relevant case of an elongated, effectively 1 + 1 dimensional, expanding condensate. In this case we include the effects of inhomogeneities in the condensate, a feature rarely included in the analogue gravity literature. In both cases we link the BEC expansion to a simple model for an expanding spacetime and then study the correlation structure numerically and analytically (in suitable approximations). We also discuss the expected strength of such correlation patterns and experimentally feasible BEC systems in which these effects might be detected in the near future.