Cold atom-based quantum technology for probing fundamental physics
File(s)
Author(s)
Pasatembou, Elizabeth
Type
Thesis
Abstract
Advancing our knowledge of the universe increasingly relies on technologies capable of extremely precise measurement. Quantum sensors have emerged as promising tools for searching for new physics by pushing the boundaries of precision in measuring time, acceleration, and gravity. Two promising platforms are long-baseline atom interferometers and atomic clocks, both of which rely on cold atoms. This thesis lies at the intersection of cold-atom physics, quantum technology, and particle phenomenology.
We report experimental progress from the AION project, a next-generation atom interferometer for the detection of ultra-light dark matter and mid-frequency gravitational waves. Within the collaboration, we present the first results from a red magneto-optical trap (MOT) for strontium-88 atoms. A seed–amplifier injection-locked laser system was developed to address the 1S0–3P1 transition at 689 nm, delivering 13.8 mW of light to the science chamber. Using this setup, we produced an atomic cloud at a temperature of (812 ± 4) nK in the narrowband red MOT, marking a critical milestone in the project.
Secondly, the potential of next-generation atomic and molecular clocks in constraining theories that violate the weak equivalence principle (EP) is investigated. A search for variations in the electron–proton mass ratio is performed using publicly available data from UTC. A statistical framework is then developed to model clock noise and forecast sensitivity to signals arising in theories of dark matter, dark energy, unification, and other EP-violating scenarios, providing new and improved constraints. The framework is packaged into a tool that translates clock noise characteristics into constraints on fundamental physics theories. A preliminary study investigating the effect of data gaps in signal recovery shows that annual signals with amplitudes above 10⁻¹⁶ can be recovered even with up to 83% missing data.
We report experimental progress from the AION project, a next-generation atom interferometer for the detection of ultra-light dark matter and mid-frequency gravitational waves. Within the collaboration, we present the first results from a red magneto-optical trap (MOT) for strontium-88 atoms. A seed–amplifier injection-locked laser system was developed to address the 1S0–3P1 transition at 689 nm, delivering 13.8 mW of light to the science chamber. Using this setup, we produced an atomic cloud at a temperature of (812 ± 4) nK in the narrowband red MOT, marking a critical milestone in the project.
Secondly, the potential of next-generation atomic and molecular clocks in constraining theories that violate the weak equivalence principle (EP) is investigated. A search for variations in the electron–proton mass ratio is performed using publicly available data from UTC. A statistical framework is then developed to model clock noise and forecast sensitivity to signals arising in theories of dark matter, dark energy, unification, and other EP-violating scenarios, providing new and improved constraints. The framework is packaged into a tool that translates clock noise characteristics into constraints on fundamental physics theories. A preliminary study investigating the effect of data gaps in signal recovery shows that annual signals with amplitudes above 10⁻¹⁶ can be recovered even with up to 83% missing data.
Version
Open Access
Date Issued
2025-08-01
Date Awarded
01/12/2025
License URL
Advisor
Baynham, Charles
Buchmueller, Oliver
Publisher Department
Department of Physics
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)