Laser Cooling of Single ^<174>Yb^+ Ions Stored in a RF Trap

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We demonstrate laser cooling of single ^<174>Yb^+ ions stored in a rf trap. Single ^<174>Yb^+ ions were loaded using a natural isotope mixture as source. To locate a single ion at the center of the trap, and consequently, to minimize the micromotion caused by the rf driving field, we introduced two compensation electrodes and applied dc voltages to them and to one of the endcap electrodes. We estimated the temperature of a trapped single ^<174>Yb^+ ion to be 150 mK from the residual Doppler width of the spectra observed by a frequency sweep of the cooling laser. In the estimation, the saturation broadening in the spectra was substituted by measurement of the power dependence of the spectral width. To count the number of trapped ^<174>Yb^+ ions, we detected sudden drops in the fluorescence intensity (quantum jumps) of individual ions caused by pumping to and deexcitation of the ^2F_<7/2> state. We found that deexcitation of the ^2F_<7/2> state is possible by driving the ^2F_<7/2>-^1D[3/2]_<3/2> transition at 760 nm and the ^2F_<7/2>-^3D[9/2]_<7/2> transition at 828 nm, in addition to the former methods of driving the ^2F_<7/2>-^1D[5/2]_<5/2> transition at 639 nm and the ^2F_<7/2>-^2D_<5/2> transition at 3.43μm.
社団法人応用物理学会の論文
1999-04-15