Emergent gravitational dynamics in relativistic Bose--Einstein condensate

TL;DR

This paper demonstrates that a relativistic Bose--Einstein condensate can serve as an analogue model of gravity, where an emergent spacetime obeys a Nordström-like gravitational equation, linking microscopic quantum matter to semiclassical gravity.

Contribution

It provides the first example of an emergent Lorentz invariant, geometric theory of gravity from a quantum matter system in flat spacetime using analogue gravity models.

Findings

Emergent spacetime with relativistic fields in a Bose--Einstein condensate.

The gravitational dynamics follow a Nordström-like equation.

Newton and cosmological constants depend on microscopic system scales.

Abstract

Analogue models of gravity have played a pivotal role in the past years by providing a test bench for many open issues in quantum field theory in curved spacetime such as the robustness of Hawking radiation and cosmological particle production. More recently, the same models have offered a valuable framework within which current ideas about the emergence of spacetime and its dynamics could be discussed via convenient toy models. In this context, we study here an analogue gravity system based on a relativistic Bose--Einstein condensate. We show that in a suitable limit this system provides not only an example of an emergent spacetime (with a massive and a massless relativistic fields propagating on it) but also that such spacetime is governed by an equation with geometric meaning that takes the familiar form of Nordstr{\"o}m theory of gravitation. In this equation the gravitational field is sourced by the expectation value of the trace of the effective stress energy tensor of the quasiparticles while the Newton and cosmological constants are functions of the fundamental scales of the microscopic system. This is the first example of analogue gravity in which a Lorentz invariant, geometric theory of semiclassical gravity emerges from an underlying quantum theory of matter in flat spacetime.