Optically Pumped Cold Cesium Beam Atomic Clock Based on Two-dimensional Magneto-optical Trap

We report the scheme and preliminary experiments of optically pumped cold cesium beam atomic clock based on two-dimensional magneto-optical trap. It is predicted that the Ramsey fringe linewidth of such atomic clock can reach 25Hz, while the output frequency stability is expected to be $\sigma_{\mathrm{y}}(\tau)=2\times 10^{-14}/\sqrt{\tau}$ .