Realization of a Two-Dimensional Magneto-optical Trap with a High Optical Depth

We build up a novel setup of a two-dimensional (2D) ⁸⁵Rb magneto−optical trap (MOT) with a high optical depth (OD) of 38. Such a MOT trap of ⁸⁵Rb has several advantages as compared to the normal three−dimensional ellipsoidal MOT. Firstly, it will greatly enhance atom-photon interaction due to the large OD. Then, the dephasing caused by the magnetic gradient will be decreased in the long axis of the 2D MOT, which we want to avoid from in the experiments. The metastable ground level dephasing rate was γ₂₁=0.008γ₃₁, which is much less than that in a normal MOT. The total number of atoms in this MOT was measured to be 9.1×10⁸.