The Influence Of The Pumping Effect Of The Cooling Light On The Atomic Population

Atoms and molecules are the smallest the elements consisting of the matter. So effectively controlling atoms is an important objector in the physics research all the time. Now the technology of laser cooling neutral atoms by laser has been developed. The combination of Cold atoms integrating with quantum optical is a hot research of the experiment group currently. When light interact with multi-level atoms, electromagnetically induced transparency (EIT) induce low absorption, strong steep dispersion and enhanced nonlinearity. The atomic medium can be applied in the enhancement of the Kerr nonlinearity and slowing down the group velocity of light. And this will provide an effective tool for the quantum phase gate and light storage.This paper mainly consists of the following parts. (1) a brief introduction of the historical development of cold atomic trapping, the Principles of trapping atoms and a description of improvement of our Rb atomic magneto-optic trap system,where cold atomic with higher optical depth is obtained, which are realized mainly by increasing the power of light cooling. (2) The influence of the cooling light cut-off time delay to the atomic population on the ground state is studied in the 87Rb MOT by the time sequentied control. In the experiment, the cooling light switch is controlled by AOM. and the relationship of the atomic population of the ground state and the cut-off time of the cooling light is analyzed。(3) In the experiment of storage and releasing of optical signal, we use a narrowband F-P interference filter whose transmission optical frequency is controlled by temperature, to eliminate the back ground from the coupling light in detecting released signal and get a high SNR reading light.The main works are as following:In the 87Rb MOT, the relationship of the atomic population in the ground state and the cut-off time of the cooling light is analyzed and the SNR of reading light is improved in light storage by the narrowband F-P interference filters.1) By using timing control switches, we can precisely change the open and closed time of the cooling light and the repumping light. The preparation and determination of the ground states in cold atoms has been achieved by delaying the closed time of the cooling light and extending the role time of the cooling light. The results show that with the cut-off time of the cooling light becoming longer, the atomic population on the F=2 state is decreasing while the atomic population on the F=1 state is increasing. The result is used to prepare the energy level of Zeeman.2) At the experiment of the storage and release of the pulse light, to eliminate the back ground from the coupling light in detecting release signal, we use the F-P interference filter whose frequency is controlled by temperature. So it eliminates the back ground of the coupling light to the results in the experiment and improves the SNR of the reading light signal.