Amplification of waves from a rotating body

Cromb, M., Gibson, G. M. , Toninelli, E., Padgett, M. J. , Wright, E. M. and Faccio, D. (2020) Amplification of waves from a rotating body. Nature Physics, 16, pp. 1069-1073. (doi: 10.1038/s41567-020-0944-3)

Abstract

In 1971, Zel’dovich predicted that quantum fluctuations and classical waves reflected from a rotating absorbing cylinder will gain energy and be amplified. This concept, which is a key step towards the understanding that black holes may amplify quantum fluctuations, has not been verified experimentally owing to the challenging experimental requirement that the cylinder rotation rate must be larger than the incoming wave frequency. Here, we demonstrate experimentally that these conditions can be satisfied with acoustic waves. We show that low-frequency acoustic modes with orbital angular momentum are transmitted through an absorbing rotating disk and amplified by up to 30% or more when the disk rotation rate satisfies the Zel’dovich condition. These experiments address an outstanding problem in fundamental physics and have implications for future research into the extraction of energy from rotating systems.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Gibson, Dr Graham and Faccio, Professor Daniele and Toninelli, Ermes and Padgett, Professor Miles and Cromb, Dr Marion
• Authors: Cromb, M., Gibson, G. M., Toninelli, E., Padgett, M. J., Wright, E. M., and Faccio, D.
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Journal Name: Nature Physics
• Publisher: Nature Research
• ISSN: 1745-2473
• ISSN (Online): 1745-2481
• Published Online: 22 June 2020
• Copyright Holders: Copyright © 2020 The Authors
• First Published: First published in Nature Physics 16:1069-1073
• Publisher Policy: Reproduced in accordance with the publisher copyright policy

Project Code	Award No	Project Name	Principal Investigator	Funder's Name	Funder Ref	Lead Dept
303021		Black Hole Superradiance in Rotating Fluids (SURF)	Daniele Faccio	Engineering and Physical Sciences Research Council (EPSRC)	EP/P006078/2	P&S - Physics & Astronomy
303359		PhoQus	Daniele Faccio	European Commission (EC)	820392	P&S - Physics & Astronomy