Spin-noise spectroscopy of a spin-one system

The spin-noise mechanisms in a spin-1 system are theoretically and experimentally investigated in detail. Eight different independent spin degrees of freedom are isolated, leading to spin-noise signals at the Larmor frequency or its second harmonic in the presence of a magnetic field. The signatures of these different modes of the detuned probe light beam polarization fluctuations, observed either as Faraday rotation noise or as ellipticity noise, are shown to depend dramatically on the probed transition. In particular, depending on the Zeeman structure of the upper level of the transitions, the different noise modes can be visible or not, and their dependence on the probe polarization can be completely modified. Those predictions are successfully compared with measurements of spin-noise signals using three different transitions of an ensemble of metastable 4He at room temperature.

Automated summary

The spin-noise mechanisms in a spin-1 system are studied in detail, both theoretically and experimentally. Different spin degrees of freedom result in spin-noise signals at the Larmor frequency or its second harmonic in the presence of a magnetic field. The dependence of the observed noise modes on the probed transition is shown to vary dramatically, depending on the Zeeman structure of the upper level of the transitions. These findings are successfully validated through measurements of spin-noise signals in an ensemble of metastable 4He at room temperature using three different transitions.