Experimental Improvement of Signal of a Single Laser-Cooled Trapped ⁴⁰Ca⁺ Ion

A single ⁴⁰Ca⁺ ion is loaded in a miniature Paul trap and the probability of directly loading a single ion is above 50%. The signal-to-noise ratio and the storage time for a single ion have been improved by minimizing the ion micromotion and locking a 397nm cooling laser to a Fabry--Perot interferometer and optogalvanic signal. From the fluorescence spectrum, the ion temperature is estimated to be about 5mK.