Microwave interrogation in a compact atomic clock

HORACE is a compact cold atom clock where the atoms are cooled inside the microwave interrogation cavity. About 108 atoms can be cooled at kinetic temperatures as low as 2.5 muK. We report for the first time Ramsey pattern observed with a 14 Hz linewidth and fringe contrast better than 80%. Since this clock is designed for Space applications, some properties are extrapolated to micro-gravity operation.