Observation of Faraday Rotation in Cold Atoms in an Integrating Sphere

The Faraday rotation of weak linearly polarized probe light is observed as it passes through a sample of cold ⁸⁷Rb atoms prepared by diffused light in an integrating sphere. The rotation angle of the probe light-polarization as functions of laser intensity, detuning and biased magnetic field is measured. A Ramsey fringe with a linewidth of 35 Hz and contrast up to 92% is demonstrated. This method has potential applications in improving the performance of atomic clocks with cold atoms.