Experimental particle production in time-dependent spacetimes: a one-dimensional scattering problem

TL;DR

This study uses a Bose-Einstein condensate to experimentally simulate cosmological particle production, revealing how spacetime expansion influences particle spectra through quantum scattering analogies.

Contribution

It demonstrates a novel experimental approach to simulate and analyze cosmological particle production using tunable interactions in a Bose-Einstein condensate, linking scattering phenomena to universe expansion models.

Findings

Observation of resonant forward scattering analogous to cosmological phenomena

Identification of Bragg reflection effects related to bouncing universe models

Extension of theoretical models to high-momentum excitations

Abstract

We experimentally study cosmological particle production in a two-dimensional Bose-Einstein condensate, whose density excitations map to an analog cosmology. The expansion of spacetime is realized with tunable interactions. The particle spectrum can be understood through an analogy to quantum mechanical scattering, in which the dynamics of the spacetime metric determine the shape of the scattering potential. Hallmark scattering phenomena such as resonant forward scattering and Bragg reflection are connected to their cosmological counterparts, namely linearly expanding space and bouncing universes. We compare our findings to a theoretical description that extends beyond the acoustic approximation, which enables us to apply the model to high-momentum excitations.