We report our studies on an intense source of cold cesium atoms based on a two-dimensional magneto-optical trap with independent axial cooling and pushing. The new-designed source, proposed as 2D-HP MOT, uses hollow laser beams for axial cooling and a thin pushing laser beam for cold atomic beam extraction. Regulated independently by the pushing beam, the atomic flux can be substantially optimized. The atomic flux maximum obtained in the 2D-HP MOT is 4.02 × 10 10 atoms/s, increased by 60 percent compared to the traditional 2D + MOT in our experiment. Moreover, with the pushing power 10 µW and detuning 0Γ, the 2D-HP MOT can generate a rather intense cold cesium atomic beam with the concomitant light shift suppressed by 20 times in magnitude. The axial velocity distribution of the cold cesium beams centers at 6.8 m/s with a FMHW of about 2.8 m/s. The dependences of the atomic flux on the pushing power and detuning are studied. The experimental results are in good agreement with the theoretical model.

We present a coherent bichromatic laser system with low phase noise. An optical injection process is used to generate coherent laser beams with a frequency difference of 9.192 631 77 GHz using an electro-optical modulator. An optical phase-locked loop is then applied to reduce the phase noise. The phase noise of the beat note is -41, -81, -98, -83, and -95 dBrad/Hz at the offset frequencies of 1 Hz, 100 Hz, 1 kHz, 10 kHz, and 1 MHz, respectively. Compared to a system that uses optical injection alone, the phase noise is reduced by up to 20-30 dB in the low-frequency range, and the intermodulation effect on the continuous atomic clock is reduced by an order of magnitude. This configuration can adjust the intensities and polarizations of the laser beams independently and reduce the phase noise caused by environmental disturbances and optical injection, which may be useful for application to atomic coherence experiments.

We report an experimental study on the temperature and number evolution of cold cesium atoms diffusively cooled inside a wall-coated glass cell by measuring the absorption profile of the 6 2 S1/2 (F=4)→6 2 P3/2 (F'=5) transition line with a weak probe laser in the evolution process. We found that the temperature of the cold atoms first gradually decreases from 16 mK to 9 mK, and then rapidly increases. The number of cold atoms first declines slowly from 2.1×10 9 to 3.7×10 8 and then falls drastically. A theoretical model for the number evolution is built and includes the instantaneous temperature of the cold atoms and a fraction p, which represents the part of cold cesium atoms elastically reflected by the coated cell wall. The theory is overall in good agreement with the experimental result and a nonzero value is obtained for the fraction p, which indicates that the cold cesium atoms are not all heated to the ambient temperature by a single collision with the coated cell wall. These results can provide helpful insight for precision measurements based on diffuse laser cooling.

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