Abstract

Crystal structures of Calcium ions are prepared in a linear Paul trap. The trapped ions are laser-cooled (λ=397nm, 866nm). Images of the fluorescing ions are obtained with a CCD-camera. Individual ions in a string are well resolved. The measured distances between ions agree well with expected values that are calculated from the ion-ion Coulomb repulsion in the harmonic trap potential [1]. The transition from the S_1/2 ground state to the metastable D_5/2 state (τ=1s) at 729nm in ⁴⁰Ca⁺ is well suited to store quantum information (q-bits). Entanglement between ions can be generated via their common modes of vibration. Using a resonant rf-field, different eigenmodes of longitudinal vibration have been excited in the string. The center-of-mass mode and higher modes of excitation have been observed (see figure).

© 1998 IEEE