This thesis reports the design, assembly and characterisation of a new cold-atom fountain clock. Diffractive optics have previously been used to produce compact atom trapping systems. I build upon that research to launch the trapped atoms upwards, as in existing fountain clocks. Those clocks launch their atoms up to a metre high, passing through a microwave cavity. I also embed the diffractive optic within a microwave cavity allowing a small, integrated apparatus. This allows an interrogation time of 100 ms, intermediate between the 10 ms to 20 ms achievable without a launch, and the 500 ms observed in a full-scale fountain.Coherent population trapping was used to test the new atomic fountain technique and observe its initial performance in a clock system, where it improved the clock by allowing a longer time-offlight, with a best single-shot stability of 2.9×10−11 The diffractive optic was then mounted inside a microwave cavity, allowing in-situ atom trapping with only a single aperture for the trapping beam. Another clock sequence was realised here, using the microwave cavity to directly excite atomic transitions. The microwave excitation doubled the detection SNR, going from 42 to 95 with potential for further increases. The future combination of the fountain and in-cavity trapping techniques will produce a miniature version of the microwave fountain clocks which are central to modern frequency metrology. An analysis has been done of the potential performance such a clock could achieve, to highlight the most critical areas of design and guide future experiments.
| Date of Award | 27 Jan 2023 |
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| Original language | English |
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| Awarding Institution | - University Of Strathclyde
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| Sponsors | University of Strathclyde |
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| Supervisor | Paul Griffin (Supervisor) & Erling Riis (Supervisor) |
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