Three dimensional light fields in atomic state interferometry

Svensson, Sphinx Jed (2025) Three dimensional light fields in atomic state interferometry. PhD thesis, University of Glasgow.

Abstract

This thesis is about the interaction of structured light with atoms in the presence of external magnetic fields. Both light and atoms can carry phase dependent structures, the expression of which often depends on the choice of quantisation axis. The most general type of spatial structure light can have manifests as polarisation patterns. This type of structure is quantified as the optical concurrence. Although polarisations are usually considered to be two-dimensional, light can also carry a longitudinal polarisation component, but it has not been directly measured before.
Atomic states can be altered by external electric and magnetic fields. These fields don’t just alter the atom’s charge density distribution, but the very state space that defines it. Additionally, it is possible to redefine atomic states as superpositions of one another in order to reveal hidden structures. Previously, the best theoretical models of structured light-matter interaction were only valid for special cases, but a generalised model can open new opportunities for describing, understanding, and ultimately measuring ambient electric and magnetic fields.
In this thesis, the energy shifts induced in atoms by strong magnetic fields have been utilised to visualise an atomic transition normally unavailable in the chosen configuration being driven by longitudinal light. At the same time, a generalised model of the atomic state interferometer is constructed, and shown to be capable of predicting new ways to measure magnetic fields and optical concurrence.
The atomic state interferometer requires only a single transmission image for these measurements, and its validity means that it is possible to look for other combinations of electric and magnetic fields that can reveal further symmetries within the atom. In addition to having a highly versatile and customisable device that can measure the interplay of electric and magnetic fields, this thesis demonstrates a spatially resolved way of investigating three-dimensional polarisation states.
Having unlocked access to a new type of polarisation, the next steps are to investigate properties of strongly focused beams that have previously been confined to the realm of theory. On the more practical side, the atomic state interferometer lends itself to sensing applications, such as the measurement of non-classical correlations between degrees of freedom in a beam. Currently, work is being done to build a miniaturised research magnetometer based on the same principles.
In short, atoms provide a good interface between classical and quantum world. Customising their available state space opens the way to a new generation of sensors.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Subjects: Q Science > QC Physics
• Colleges/Schools: College of Science and Engineering > School of Physics and Astronomy
• Funder's Name: UK Research and Innovation ( UKRI) (UKRI)
• Supervisor's Name: Franke-Arnold, Professor Sonja and Westerberg, Dr. Niclas
• Date of Award: 2025
• Depositing User: Theses Team
• Unique ID: glathesis:2025-85382
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 12 Aug 2025 14:08
• Last Modified: 12 Aug 2025 14:10
• Thesis DOI: 10.5525/gla.thesis.85382
• URI: https://theses.gla.ac.uk/id/eprint/85382

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