Shielding of Penrose superradiance in optical black holes

Abstract

We investigate the effect of superradiance shielding for the analogue rotating black holes simulated by optical vortices by calculating the radial motion of massless particles in such spacetime background. We add the conditions $$E<L\Omega _{r_{e}}$$ E < L Ω r e and $$L>0$$ L > 0 to judge the classically forbidden region of superradiance. It is found that the superradiance forbidden region exists near the static limit inside the ergosphere, which will limit the classical Penrose process for the particles with some specific energies and angular momenta. Once these particles satisfying the superradiance conditions are measured at the outside of the ergosphere, this shows that the Penrose process can be quantum.

Penrose Scattering in Quantum Vacuum

“…Here, we propose another possible configuration, which is directly inspired by traditional optical experiments using rotating mirrors, and that more recently was recreated in a gravitational context. This new context was first explored by Penrose [15], Zeldovich [16] and others as a way to extract energy from a rotating black hole, and it is sometimes called Penrose superradiance [17,18]. Recent observations of similar phenomena were claimed in nonlinear optics [19], in acoustics [20], and in hydrodynamics [21].…”