Optimization Of ²³Na⁴⁰K Bose-Fermi Mixture Apparatus

With the continuous development of science and technology,people are increasingly updating their tools for exploring the cryogenic world.And the study of singular cryogenic physics has never stopped.The third law of thermodynamics:It can only get close to zero Kelvin and cannot achieve.Technically,lowering the temperature from 1K to 0.1K is much more difficult than raising the temperature from 100K to1000K.After 100 years of hard efforts,especially represented by laser Cooling and evaporative Cooling technology,the limiting temperature of laboratory dropped by about 10⁹ times from hundreds Kelvin in the year of 1877 to the level of nanokelvin,this is an unprecedented progress.The macroscopic condensation of dilute alkali metal atomic gases such as Bose Einstein condensate,Fermi gas degeneracy,and supercooled molecular carriers has provided a more abundant experimental platform for condensed matter physics at nanokelvin.A quantum simulator based on an ultracold atom molecular platform with an artificially adjustable Zeeman effect,AC Stark effect,magnetic Feshbach resonance,photoassociation,and STIRAP has exerted unparalleled advantages than other platforms in the studies such as neutral atoms optical lattices,superconductor theory of BEC-BCS Crossover,and polar molecules.Among them,the ultracold polarity molecule is also an unexceptionable simulation model.It also provides excellent experimental objects for the study of new quantum states of matter,the improvement of the measurement accuracy of basic physical constants,and the study of basic principles of quantum information and calculation.In the past decade,research on ultracold molecules has come a long way.The use of magnetic Feshbach resonances to regulate interatomic interactions allows the adiabatic transfer of two independent atoms from the non-bound state to the weakly bound state,and the STIRAP transition technique transform the weakly bound state molecule from the highly excited state to the ground state of rotation-vibration energy level.For the first time in the world,⁴⁰K⁸⁷Rb ultracold molecules have been realized.However,the chemical exchange reaction of ⁴⁰K⁸⁷Rb molecule is not stable,so it is difficult to continue the evaporative Cooling to obtain the quantum degeneracy of the dipole molecule.²³Na⁴⁰K and ⁴⁰K¹³³Cs are the only two chemically stable alkali metal dipolar fermion molecule.They are expected to overcome the stability problem of⁴⁰K⁸⁷Rb molecule and achieve quantum degeneracy of the molecule.Among them,the dipole moment of ²³Na⁴⁰K molecule is larger,it's 2.72 Debye.This thesis mainly focused on the ultracold dipolar gas of fermionic ²³Na⁴⁰K molecules experiment in IOP:1,I have experimentally debugged the problem of stability of the system.Such as the variation of environment temperature,stray magnetic field,the impact on the magnetic trap atoms by high speed atom flux from the oven and so on.After optimizing the parameters,I successfully acquired a Na BEC of6×10⁶ with the help of the hybrid trap.2,I have optimized the performance of ⁴⁰K 2D⁺MOT and captured 5.4×10^{6 40}K MOT from the natural abundance metal potassium finally,which reduced the cost of the experiment greatly.3,I introduced the process of loading the dual-species MOT in 3D MOT and MT after optical pumping.