Investigation Of Feshbach Resonance Experiment System Based On ~6Li Ultra-Cold Fermion Gas Experiment

Since the Bose-Einstein condensation,the fifth form of matter,was realized in experiment in 1995,the study of ultra-cold atomic systems has experienced unprecedented development.Especially in recent years,ultra-cold Fermi gases have attracted considerable interest in experimental and theoretical research.In cold-atom experiments,the laser cooling techniques can effectively slow down the atomic beams and can realize the trapping of atoms in MOT,while the technique of Feshbach resonance can precisely control the interatomic interactions.These techniques have extensive applications in the experiments of degenerate atomic Fermi gases and molecular Bose-Einstein condensates.This thesis mainly includes two research works.First,we have designed and optimized the magnetic fields needed in the experiment of ultra-cold Fermi gas of lithium atom,such as MOT magnetic field,Feshbach resonance magnetic field and Zeeman slowing magnetic field.In terms of the optimized design of the MOT coil and Zeeman slower,we can effectively slow down the atomic beams and trap the atoms in MOT,and then significantly improve the capacity of trapping atoms in magnetic and optical trap.For instance,the magnitude of the number of the atoms has been increased from the sixth power of ten to the eighth power of ten.At the same time,we have measured and tested the magnetic field gradient of the MOT magnetic field and Feshbach resonance magnetic field.It is proved that the design and processing of the magnetic fields can meet our experimental requirements.Second,we have designed a control system for the Feshbach resonance magnetic field that can work effectively.It can realize the millisecond level quick turn-off from zero to 520 A,and 1200 G Feshbach resonance magnetic field.By using the control system of the Feshbach resonance magnetic field and combining with the cooling methods such as the Zeeman slower?MOT and trapping via the dipole trap,we can prepare an ultra-cold Fermi gas of lithium atoms.This work lays a solid experimental foundation for realizing the quantum degeneracy of the Fermi gas of lithium-6 atoms and for further study of BEC-BCS transition and two-body correlation effects?...