Electromagnetically induced transparency in a Zeeman-sublevels Λ-system of cold ⁸⁷Rb atoms in free space

We report the experimental investigation of electromagnetically induced transparency (EIT) in a Zeeman-sublevels Λ-type system of cold ⁸⁷Rb atoms in free space. We use the Zeeman substates of the hyperfine energy states 5² S_1/2, F=2 and 5² P_3/2, F'=2 of ⁸⁷Rb D₂ line to form a Λ-type EIT scheme. The EIT signal is obtained by scanning the probe light over 1 MHz in 4 ms with an 80 MHz arbitrary waveform generator. More than 97% transparency and 100 kHz EIT window are observed. This EIT scheme is suited for an application of pulsed coherent storage atom clock (Yan B, et al. 2009 Phys. Rev. A 79 063820).