Rotating black hole geometries in a two-dimensional photon superfluid

TL;DR

This paper demonstrates a 2+1D photon superfluid system that mimics rotating black hole geometries, providing the first experimental evidence of an ergosphere and horizon in an analogue gravity setup.

Contribution

It introduces a novel 2+1D photon superfluid platform to realize and observe rotating black hole analogues in laboratory conditions.

Findings

Identification of an ergosphere and event horizon in the superfluid

First experimental evidence of a rotating black hole analogue in 2+1D

Potential to study Penrose superradiance and quantum effects

Abstract

Analogue gravity studies the physics of curved spacetime in laboratory experiments, where the propagation of elementary excitations in inhomogeneous flows is mapped to those of scalar fields in a curved spacetime metric. While most analogue gravity experiments are performed in 1+1 dimensions (one spatial plus time) and thus can only mimic only 1+1D spacetime, we present a 2+1D photon (room temperature) superfluid where the geometry of a rotating acoustic black hole can be realized in 2+1D dimensions. By measuring the local flow velocity and speed of waves in the superfluid, we identify a 2D region surrounded by an ergo sphere and a spatially separated event horizon. This provides the first direct experimental evidence of an ergosphere and horizon in any system, and the possibility in the future to study the analogue of Penrose superradiance from rotating black holes with quantised angular momentum and modified dispersion relations.