Realization Of Spin Tensor-momentum Coupling In Degenerate Fermi Gases And Experimental Study On Rydberg Excited State

Since the experimental realization of Bose-Einstein condensates,ultra-cold atoms have become a very important platform for people to study quantum phenomena.Artificial gauge fields be used to achieve spin-orbit coupling in neutral atoms to simulate phenomena that are difficult to observe in solid materials,such as:topological insulators,quantum Hall effect,etc.Optical Feshbach resonance are such powerful tools and has been widely used in studying strongly correlated degenerate atomic gases.In addition,Rydberg atoms have the characteristics of long lifetime,large radius,and easy ionization.In recent years,the research of Rydberg atoms and the application of electromagnetically induced transparency(EIT)have also become hotspots,such as the preparation of single photon sources and the realization of quantum logic gates.This thesis mainly introduced our experiments on the basis of quantum fermionic ⁴⁰K,including the preparation of 50/50 mixed state in ultracold Fermi gas,experimental realization of a spin-tensor momentum coupling in ultracold Fermi gases,and the measurement of Rydberg excited spectrum of ultracold ⁴⁰K atoms by using electromagnetically induced transparency effect.We make a comprehensive upgrade and improvement to our experimental system:change the original first-level three-dimensional magnetic optical trap(MOT)to a two-dimensional magnetic optical trap,and redesign the optical path and magnetic field coil accordingly;We put ultraviolet light at the first-level MOT windows to removes the atoms adsorbed on the wall of the gas chamber to increase the rate of atom capture.The original bright MOT is changed to dark MOT to increase the density of the atom cloud.The compensation coil is used to reduce the fluctuation of the magnetic field by the undulate of water temperature,and eliminate the environmental noise of the system.We report a novel method to prepare a mixture of ⁴⁰K Fermi gas having an equal population of the two ground magnetic spin states.We realize the equal population mixture by applying a series of Radio-Frequency(RF)pulses.We adopted the theoretical plan proposed by Professor C-W Zhang's group at the University of Texas at Dallas,and experimental realized the spin tensor-momentum coupling(STMC),and measured the spin-injection spectrum and momentum resolution spectrum of STMC.And prove that the intermediate state is a dark state.In ⁴⁰K ultracold fermi gas,a ladder type system,we measured the Rydberg excited spectrum of ns and nd.Two different methods are employed to measure the spectrum using different powers of the probe laser.One scheme is to reduce atomic losses by means of EIT.The second method is to enhance the atomic losses by the spontaneous avalanche ionization.In addition,we observed an additional state which is the dipole forbidden transition.