Implementation And Optimization Of The Two-dimesional Magneto-optical Trap Of ⁴⁰K Of Natural Abundance

Since the firstly realization of Bose-Einstein condensate in 1995 and the quantum-degenerate Fermi gas in 1999,one major focus of research in the field of atomic,molecular and optical physics lay on the creation and the relevant research of ultracold diatomic dipolar molecules.Because of larger electron dipole moment and chemical stability,23Na⁴⁰ K polar molecule became our choice.The first step to realize ultracold dipolar molecule is loading of two-species magneto-optical trap（MOT）.Larger atomic number and loading rate are very important for our experiment for following reasons.Firstly,in the process of evaporation,lots of atoms will lose,especially the number of bosonic 23 Na used for sympathetically cooling fermionic ⁴⁰ K.Secondly,a large initial atom number makes the evaporation procedure more efficient.Finally,the Fermi temperatures of fermions are higher and thus quantum degeneration can be observed at higher temperatures.Usually,the loading rate of Zeeman slower and 2D-MOT（two-dimensional magneto-optical trap）are higher than others and offer efficient loading.Due to the sodium vapor pressure at room temperature is lower,for example,several hundred degrees Celsius required,using Zeeman slower is better.In our experimental setup,we used Zeeman slower to loading the MOT of sodium,and we have achieved 23 Na MOT with the atomic number of 2×1010 and loading rate of 3×109/s.But for potassium,only proper vapor pressure can be achieved by heating to tens of degrees Celsius.However,since the low natural abundance of ⁴⁰ K,only about 0.012%,we used 2D⁺-MOT to load the ⁴⁰ K MOT.In this thesis,we introduce the production of 5×106 atoms in MOT by 2D⁺-MOT with natural K-sample.