Loading of atoms into an optical trap with high initial phase-space density

We report a method for loading cold atoms into an optical trap with high initial phase-space density (PSD). When the trap beam is overlapped with atoms in optical molasses of optimized parameters including large cooling beam detuning compared with conventional detuning used for a magneto-optical trap (MOT), more than $3 \times 10^6$ rubidium atoms with an initial temperature less than 20 $\mu$K are loaded into a single beam trap. The obtained maximum initial PSD is estimated to be $1.1 \times 10^{-3}$, which is one or two orders of magnitude greater than that achieved with the conventional loading into an optical trap from atoms in a MOT. The proposed method is promising for creating a quantum gas with a large number of atoms in a short evaporation time.