Heterodyne measurement of the fluorescent radiation of a single trapped ion

The spectrum of the fluorescent radiation of a single trapped Mg-24(+)-ion at low excitation intensity was investigated. The measurement was performed by heterodyning the fluorescent radiation with a sideband of the single mode laser radiation used to excite the ion, resulting in a linewidth of 6 Hz. Under identical experimental conditions, the antibunching in the photon statistics of the fluorescent radiation was also investigated. Heterodyne detection and photon correlation measurement are complementary featuring either the wave or the particle nature of the radiation. The combination of both techniques will allow to measure squeezing in resonance fluorescence.