Investigating a qubit candidate: Spectroscopy on the S-1/2 to D-5/2 transition of a trapped calcium ion in a linear Paul trap - art. no. 023405

A single Ca-40(+) ion is confined in a linear Paul trap and Doppler-cooled on the S-1/2 to P-1/2 dipole transition. Then the narrow quadrupole S-1/2 t o D-5/2 transition at 729 nm is probed. The observed spectrum is interprete d in terms of the Zeeman substructure superimposed with oscillation sideban ds due to the harmonic motion in the trap. The height of the motional sideb ands provides a sensitive method to determine the ion's temperature and thu s allows us to test sub-Doppler laser cooling schemes needed for quantum st ate preparation and quantum computation. We also observe the dynamics induc ed by Rabi oscillations on a carrier transition and interpret it in terms o f the thermal state which is reached after Doppler cooling.