Quantum effects and novel physics in rotating frames

Cromb, Marion (2023) Quantum effects and novel physics in rotating frames. PhD thesis, University of Glasgow.

Abstract

The birth of quantum physics and general relativity were two revolutions in physics. But a century later, scientists have not yet united the two theories. Attempts to combine them are mostly theoretical; controlled experiments have historically been neglected due to the comparative weakness of gravity and the corresponding precision or extreme scales assumed needed to test quantum gravity effects.

We take a new approach, inspired by Einstein’s equivalence of gravitational fields and accelerated frames. Non-inertial frames can be controlled in the lab, and allows us to experimentally test new frame-dependent effects and already-established quantum effects in new regimes. This frame-dependence is fundamentally interesting by itself, but also provides parallels to curved spacetime effects. To that effect, I have carried out experiments in rotating frames and shown new effects.

I have combined mechanical rotation with acoustics, sending sound waves through a rotating absorber. With this, I was the first to show experimental proof of the Zel’dovich effect: the amplification of waves carrying angular momentum by a rotating object. It is theorised the Zel’dovich effect should also generate electromagnetic waves out of the quantum vacuum, however the conditions are much harder to meet.

I have also done optics experiments to show how rotation can affect quantum entanglement. The Hong-Ou-Mandel effect was used as a witness for antisymmetric entanglement between photons. The symmetry of frequency entangled photon pairs can be manipulated by introducing path superpositions and controlling their phase difference. Through experiment I established that to witness antisymmetry with the Hong-Ou-Mandel effect it was much easier in the regime where the superposed paths had path length differences outwith the single-photon coherence length. Within a rotating frame, a rotation-dependent phase difference between counterpropagating beams of light appears, called the Sagnac effect. Combining Sagnac interferometers with a Hong-Ou-Mandel interferometer on a rotating platform, I have shown how rotation can control the entanglement symmetry of photon pairs.

The success of these experiments can be built on in future experiments exploring quantum effects in rotating frames and curved spacetimes. Identifying these effects has relevance in fundamental physics and to new technologies e.g. quantum communication, as it scales up to satellites in the curved spacetime around the rotating Earth.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Subjects: Q Science > QC Physics
• Colleges/Schools: College of Science and Engineering > School of Physics and Astronomy
• Supervisor's Name: Faccio, Professor Daniele
• Date of Award: 2023
• Depositing User: Theses Team
• Unique ID: glathesis:2023-83438
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 20 Feb 2023 16:41
• Last Modified: 21 Feb 2023 09:07
• Thesis DOI: 10.5525/gla.thesis.83438
• URI: https://theses.gla.ac.uk/id/eprint/83438

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