Relativistic Bose-Einstein Condensates: a new system for analogue models of gravity

TL;DR

This paper explores relativistic Bose-Einstein condensates as a novel analogue model for gravity, revealing unique features like dual quasi-particle excitations and generalized geometries, with potential for simulating diverse spacetime structures.

Contribution

It introduces relativistic Bose-Einstein condensates as a new analogue gravity system with distinct relativistic features and broader geometric simulation capabilities.

Findings

Presence of both massless and massive quasi-particles

Generalized acoustic metric allowing non-conformally flat geometries

Potential to study Lorentz symmetry at different energy scales

Abstract

In this paper we propose to apply the analogy between gravity and condensed matter physics to relativistic Bose-Einstein condensates (RBECs), i.e. condensates composed by relativistic constituents. While such systems are not yet a subject of experimental realization, they do provide us with a very rich analogue model of gravity, characterized by several novel features with respect to their non-relativistic counterpart. Relativistic condensates exhibit two (rather than one) quasi-particle excitations, a massless and a massive one, the latter disappearing in the non-relativistic limit. We show that the metric associated with the massless mode is a generalization of the usual acoustic geometry allowing also for non-conformally flat spatial sections. This is relevant, as it implies that these systems can allow the simulation of a wider variety of geometries. Finally, while in non-RBECs the transition is from Lorentzian to Galilean relativity, these systems represent an emergent gravity toy model where Lorentz symmetry is present (albeit with different limit speeds) at both low and high energies. Hence they could be used as a test field for better understanding the phenomenological implications of such a milder form of Lorentz violation at intermediate energies.