The superradiant amplification in the scattering from a rotating medium was first elucidated by Sir Roger Penrose over 50 years ago as a means by which particles could gain energy from the rotating spacetime surrounding Kerr black holes.

In a recent work, selected as an Editors’ Suggestion in Physical Review Letters, the analogue of this process has been demostrated in a superfluid of photons, where Bogoliubov excitations act as massless particles in the Penrose picture and an optical vortex simulates the rotating spacetime geometry on which these particles can propagate.

This observation is the result of a long-standing collaboration between researchers from Heriot-Watt University, the University of Glasgow, the University of Arizona and the CNR-INO.

Measurement of Penrose Superradiance in a Photon Superfluid
Maria Chiara Braidotti, Radivoje Prizia, Calum Maitland, Francesco Marino, Angus Prain, Ilya Starshynov, Niclas Westerberg, Ewan M. Wright, and Daniele Faccio
Phys. Rev. Lett. 128, 013901 – Published 4 January 2022