Proposal of a Novel Compact Cold Atomic Fountain Clock

We propose a novel atomic fountain clock which is compact and transportable. The clock is 60-cm in height. Its linewidth is expected to be 1.75 Hz, with accuracy 10^-14, stability 10^-14 and signal-noise ratio 10³. A hollow beam is applied as atomic wave-guide, which can increase the stability and the signal-noise ratio by one order. The hollow beam will not affect the accuracy of the clock, if the frequency shift due to the hollow beam is amended and the fluctuation of the hollow beam intensity is controlled to be smaller than 0.6%.