| The ultracold 23Na40K ground state molecule is an ideal platform for studying interections in dipoler gas,ultracold chemistry reaction processes,precision measure-ments,and etc.This thesis describes author's relevant work after joining the lab of Quantum Simulation in Ultracold Molecules at late 2012.Around the goal on forming ultracold 23Na40K ground state molecules in lab,firstly the frame of the experimental system is presented,and the details of design,construction process and experimental results are introduced.Secondly the atom physics theory related to the experiment and the techniques in producing ultracold atoms from thermal atom gases are described.Thirdly the molecule theory and the key point of successful experimental process on forming ultracold 23Na40K ground state molecules are presented.After the comprehensive description of experimental process,the study and dis-cussion on the quantum interference phenomenon during adiabatic passage of trans-ferring Feshbach molecules to ground state molecules are presented in thesis.STI-RAP(Stimulated Raman adiabatic passage)is a widely used technique in forming ul-tracold ground state molecules.When the process involves multiple channels,whether the formed ground state molecules are in a coherent superposition state or not,and the purity of the formed ground state molecules were not clearly concluded before.In this thesis,it is proved by a design experiment that if multiple channels are involved in the adiabatic molecular state transfer process,the obtained ground state molecules will be in a superposition state rather than a mixed state.The long-term coherence time of the superposition state molecules and the oscillation of molecule number is observed,and a simple method for determining the purity of molecules is provided.The quantum inter-ference phenomenon with multi-channel is universal to STIRAP,and it is also helpful for further study of ultra-cold ground state molecules. |
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