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Free keywords:
ION COULOMB CRYSTALS; LASER-COOLED IONS; PAUL TRAP; FREQUENCY STANDARD;
SPATIAL HARMONICS; MASS FILTER; STORED IONS; MINIMIZATION; ORDERPhysics;
Abstract:
We demonstrate a simple method to directly measure the micromotion speed and amplitude of ions far away from the nodal line of the linear quadrupole trap using the cross-correlation technique. For the ions very close to the trap nodal line, the micromotion speed and amplitude of ions can also be deduced through linear fitting. This work gives us a direct picture to the ions' micromotion modes at different displacements in the linear trap. With this work, an absolute measurement of the second-order Doppler effect in the research of atomic clocks based on large number of ions becomes possible. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3457904]