Abstract

We measure phase-dependent optical noise in the radiation emitted by coherently driven, long-lived two-level atoms in an atomic beam that is resonant with a preparation field that the atoms traverse. The total noise measured in the experiments contains contributions from phase-dependent Bloch- vector projection noise, spontaneous-emission, noise, and phase-dependent Poisson noise due to the moving optical dipoles that traverse the preparation region. Noise spectra are measured by using a new homodyne detection scheme in which signals from two identically prepared atomic samples are subtracted as described below. The shape and magnitude of the measured noise spectra are found to be in good agreement with predictions using no free parameters.

© 1995 Optical Society of America