Thai M. Hoang, Sang K. Chung, Thanh Le, John D. Prestage and Nan Yu, Jet Propulsion Laboratory, California Institute of Technology,

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Modern communication and navigation systems are increasingly relying on timing signals provided by atomic clocks. As timing precision requirements increase, demands for lower SWaP (size, weight, and power) clocks rise. In the atomic clock development, there is a general trade-off trend between the clock stability performance and SWaP. However, it has been challenging to break through the general trade-off trend as a higher performance atomic clock usually requires more atoms, better vacuum, higher laser powers, and complicated system and environment control, leading to a larger size and higher electric power consumption. In this talk, we will describe micro mercury trapped ion clock (M2TIC) prototypes integrated with novel micro-fabricated technologies to simultaneously achieve high performance and low SWaP. We have developed miniature vacuum trap tubes with field-emitter-arrays (FEA) electron source, 194-nm microplasma lamps, and 40.5-GHz CMOS-based microwave synthesizers. The M2TIC prototypes could reach the $10^{-14}$-stability level in one day with a SWaP of 1.1 L, 1.2 kg, and under 6 W of power. This stability level is comparable to the widely used rack-mount Microchip 5071A cesium frequency standard. These standalone prototypes survived regular shipping across the North American continent to a government laboratory, where their performance was independently tested. The M2TIC demonstration opens opportunities for high-performance clocks in terrestrial and space applications.