High-Accuracy Microwave Atomic Clock via Magic Optical Lattice
  A microwave atomic clock scheme based on Rb and Cs atoms trapped in optical lattice with magic wavelength for clock transition is proposed. The ac Stark shift of clock transition due to trapping laser can be canceled at some specific laser wavelengths. Comparing with in fountain clock, the cavity related shifts, the collision shift, and the Doppler effect are eliminated or suppressed dramatically in atomic clock when the magic optical lattice is exploited. By carefully analyzing various sources of clock uncertainty, we conclude that a microwave atomic clock with an accuracy of better than $2\times10^{-17}$ is feasible, which is of the same accuracy as the expected best optical atomic clock. 
Xiaoji Zhou, Xuzong Chen, and Jingbiao Chen