A grating-chip atomic fountain

Cold atom fountain clocks provide exceptional long term stability as they increase interrogation time at the expense of a larger size. We present compact cold using grating magneto-optical trap to laser cool and launch atoms in simplified optical setup. The is evaluated coherent population trapping demonstrates improved single-shot from launch. Ramsey times up 100 ms were measured with corresponding fringe linewidth 5 Hz. This technique could improve both short- long-term stabilities while remaining for portable applications.