Active optics for the interrogation of a single ion

The signal-to-noise ratio in the detection of a single ion is one of the determining factors in the speed of the detection of the ion's internal states. Its value defines the necessary interrogation time to distinguish between an ion in the ”on” and an ion in the ”off” state. The improvement of the detection signal by means of active optics is a new approach in single-ion experiments. They accompany further progress in the stabilization of the clock laser for the single ion interrogation.