Performance of a Laser-Induced Resonance Raman Clock

We have stabilized a microwave oscillator using a laser induced resonance Raman transition in a sodium atomic beam and have achieved plfractional frequency (clock) stability of 1.5 x 10 for a 1000 sec averaging time. This stability, which is near the shot noise limit for the present setup, compares favorably with the fractional frequency stabilities of commercial cesium clocks at 1000 sec averaging times when differences in transit time and transition frequency are taken into consideration. These preliminary results are very encouraging and were made possible because the major sources of frequency error have been identified and greatly reduced. Remaining sources of long term frequency shifts are still under investigation.