The Study Of Interaction Between Partially Coherent Light And Atom

The study of interaction between light and atom has always being an important research content in quantum optics and atomic optics,derived from which there are plentiful theories and experiments widely being used in scientific research and life.In this paper,the coherence of partially coherent light after interacting with thermal atom is explored.Besides,the coherence of cold atoms trapped by the partially coherent light is studied experimentally and theoretically.In experiments,on the basis ofstable frequency and power of the laser,we obtain the light with adjustable coherence by modulating lithium niobate crystal.After injecting the laser into rubidium vapor,the coherence of output light can be improved in a certain temperature range.With temperature rising,its coherence becomes worse.Using the partially coherent light capturing atoms,we build a cold atomic system.After measuring the number and temperature of the cold atomic cloud,we find that if the coherence of the cooling light deteriorating,the number of captured atoms remains the same,but the atomic temperature increases.Next,the microwave Rabi oscillation of the atomic cloud were measured,and the results show that the Rabi oscillation remains the same for the atoms trapped by different light beam with different coherence degree,indicates that cold atoms prepared by different coherence lasers have the same coherence characteristics and also the same capability of anti-jamming.In theory,we explain the phenomenon that the coherence of partially coherence beam(PCB)becomes better after transporting in absorption medium in the viewpoint of spectral density.With the increase of temperature,the coherence enhances while medium refractive index makes the coherence aggravated,the opponent cause the coherence of the light appearing to get better at first and worse then.Then we analyze the light force on cold atoms in PCB field.Firstly,we calculate the distribution of the light force induced by lithium niobate crystal under modulated.On the basis of results before,the more general item,random phase,is introduced into the light field.With the aid of the optical Bloch equation,the distribution of the light force is obtained.It is found that the higher of changing rate and the greater amplitude of the random phase,the more influence on the light force.We expect that our research can deepen the field of the interaction between partially coherent light and atom,and furtherly play a guiding role in the future precision measurement field.