Measurement of Penrose superradiance in a photon superfluid

Braidotti, M. C., Prizia, R., Maitland-Warne, C., Marino, F., Prain, A., Starshynov, I. , Westerberg, N. , Wright, E. M. and Faccio, D. (2022) Measurement of Penrose superradiance in a photon superfluid. Physical Review Letters, 128, 013901. (doi: 10.1103/PhysRevLett.128.013901)

Abstract

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 rotating black holes. Despite this fundamental process being ubiquitous also in wave physics, it has only been observed once experimentally, in a water tank. Here, we measure this amplification for a nonlinear optics experiment in the superfluid regime. In particular, by focusing a weak optical beam carrying orbital angular momentum onto the core of a strong pump vortex beam, negative norm modes are generated and trapped inside the vortex core, allowing for amplification of a reflected beam. Our experiment demonstrates amplified reflection due to a novel form of nonlinear optical four-wave mixing, whose phase-relation coincides with the Zel'dovich-Misner condition for Penrose superradiance in our photon superfluid, and unveil the role played by negative frequency modes in the process.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Braidotti, Dr Maria Chiara and Maitland-Warne, Calum and Prizia, Radivoje and Prain, Dr Angus and Faccio, Professor Daniele and Starshynov, Mr Ilya and Westerberg, Dr Niclas
• Authors: Braidotti, M. C., Prizia, R., Maitland-Warne, C., Marino, F., Prain, A., Starshynov, I., Westerberg, N., Wright, E. M., and Faccio, D.
• College/School: College of Science and Engineering > School of Physics and Astronomy
• Journal Name: Physical Review Letters
• Publisher: American Physical Society
• ISSN: 0031-9007
• ISSN (Online): 1079-7114