Compact ultra-cold and thermal atomic clocks with stabilities better than part-per-trillion at one second

In this talk, I will outline two stands of our ongoing atomic clock research at the University of Strathclyde, aimed at achieving short-term stabilities surpassing 1e-12 in portable systems. Firstly, I present a cold-atom microwave clock that integrates a grating-MOT within an additively manufactured microwave cavity, enabling a compact and potentially highly stable portable system. The work examines noise minimisation techniques through direct comparison with a cold-atom coherent population trapping (CPT) clock. I will also discuss progress on two-photon rubidium clocks based on MEMS vapour cells with integrated optics. The results highlight their prospects for resilient PNT applications and scalable deployment.