Progress Toward an Atomic Clock Based on a Continuous Cold Rubidium Beam

We reported on the progress toward an atomic clock based on a continuous cold 87Rb atomic beam. The atomic beam source is generated directly from a 2D
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Magneto-Optical Trapping (MOT) with the flux of about 3×10
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atoms/s and mean longitudinal velocity of 10 m/s. The beam had a free evolution time of 9 ms over the separated distance of 90 mm, producing a 54-Hz-wide Raman-Ramsey fringe. The Signal-to-Noise ratio (SNR) of Raman-Ramsey fringes is effectively increased by modulation and demodulation methods, which offer a promising approach to improving the frequency stability of the atomic clock.