Abstract: 87Rb atoms can be cooled below the Doppler cooling limit by using the decompressed magneto-optical trap (DCMOT) technique. Cold rubidium atoms are trapped in magneto-optical trap (MOT), and the temperature of cold atoms is further lowered by decreasing the magnetic field gradient and repumping light power, increasing the detuning of cooling light. The optimal experimental parameters are obtained by investigating the relationship between atomic density after free flight with the magnetic field gradient, power of repumping light and detuning of cooling light. etween atomic density of time-of-flight (TOF) and each one of the three parameters. The atom temperature is 129 measured with DCMOT, which is lower than Doppler cooling limit temperature of Rubidium 87 atom (144 ). The cold atoms are loaded directly into the magnetic trap with a loading efficiency of 25%.

Key words: magneto-optical trap, Doppler cooling limit, decompressed magneto-optical trap, compressed magneto-optical trap, polarization gradient cooling