Probing semiclassical analogue gravity in Bose--Einstein condensates with widely tunable interactions

TL;DR

This paper explores how Bose-Einstein condensates with tunable interactions can serve as analogue models for semiclassical gravity, enabling the simulation of quantum field effects in curved spacetime and potentially observable phenomena like particle production.

Contribution

It proposes using controlled tuning of scattering length in BECs to experimentally simulate and study semiclassical quantum gravity effects, including particle production in expanding universes.

Findings

Tunable scattering length in BECs can mimic varying speed of light in effective metrics.

Predicted quantum effects in BECs are larger than Hawking radiation, improving detection prospects.

Experimental feasibility of testing semiclassical gravity phenomena with current BEC technology.

Abstract

Bose-Einstein condensates (BEC) have recently been the subject of considerable study as possible analogue models of general relativity. In particular it was shown that the propagation of phase perturbations in a BEC can, under certain conditions, closely mimic the dynamics of scalar quantum fields in curved spacetimes. In two previous articles [gr-qc/0110036, gr-qc/0305061] we noted that a varying scattering length in the BEC corresponds to a varying speed of light in the ``effective metric''. Recent experiments have indeed achieved a controlled tuning of the scattering length in Rubidium 85. In this article we shall discuss the prospects for the use of this particular experimental effect to test some of the predictions of semiclassical quantum gravity, for instance, particle production in an expanding universe. We stress that these effects are generally much larger than the Hawking radiation expected from causal horizons, and so there are much better chances for their detection in the near future.