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Sympathetic Ground State Cooling and Time-dilation Shifts in an 27Al+ Optical Clock



Jwo-Sy Chen, Samuel M. Brewer, David B. Hume, Chin-Wen Chou, David J. Wineland, David R. Leibrandt


We report Raman sideband cooling of 25Mg+ to sympathetically cool the secular modes of motion in a 25Mg+-27Al+ two-ion pair to near the three-dimensional (3D) ground state. The evolution of the Fock state distributions during the cooling process is studied using a rate-nist-equation simulation, and various heating sources that limit the efficiency of 3D sideband cooling in our system are discussed. We characterize the residual energy and heating rates of all the secular modes of motion and estimate a secular motion time-dilation shift of -(1.92 +/- 0.11)* 10^{-18} for an 27Al+ clock at a typical clock probe duration of 150 ms.
Physics Review Letters


laser cooling, optical clock
Created February 3, 2017, Updated September 26, 2017