Biphotons for nonlinear imaging

Afxenti, Ivi (2026) Biphotons for nonlinear imaging. PhD thesis, University of Glasgow.

Abstract

The harnessing of the nonclassical properties in photon pairs generated by the process of Spontaneous Parametric Down Conversion (SPDC) to enhance two-photon interactions has long intrigued researchers. Their use in light-matter interactions has been proven to improve efficiency either by increasing the rate of generation or by suppressing noise. Namely, the processes of Entangled Sum Frequency Generation (eSFG) and Entangled Two Photon Absorption (eTPA) have been shown to produce more photons when stimulated with entangled photons than the classical versions of the effects. This has only been effective so far at very low intensities, which, alongside the inability to reproduce previous experimental results, has caused debates about the usefulness of the effect. In the presented work, I aim to shed light on the topic by employing a carefully crafted source of entangled photon pairs to improve two-photon effects. I attempt to demonstrate, through a series of experiments, that the quantum enhancement can be observed at an order of magnitude higher than previously thought possible. To solidify the results, a direct comparison of the quantum effect was conducted by investigating the performance of the phenomenon when it is stimulated by classical radiation from a laser. Our results confirm a quantum improvement in a regime previously considered impossible, and they enabled us to examine the ramifications of the effect on imaging. By doing so, we consider real-life microscopy applications, and therefore, we can set limits to the effect.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Subjects: T Technology > TA Engineering (General). Civil engineering (General)
• Colleges/Schools: College of Science and Engineering > School of Engineering
• Supervisor's Name: Clerici, Professor Matteo and Faccio, Professor Daniele
• Date of Award: 2026
• Depositing User: Theses Team
• Unique ID: glathesis:2026-85785
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 04 Mar 2026 14:05
• Last Modified: 04 Mar 2026 14:06
• Thesis DOI: 10.5525/gla.thesis.85785
• URI: https://theses.gla.ac.uk/id/eprint/85785

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