Spin-Orbit Coupling In Quantum Degenerate Fermi Gas

Recently, people experimentally realized an optically synthesized magnetic field for ultracold neutral atoms. With a suitable lattice configuration, it should be possible to reach the quantum Hall regime, potentially enabling studies of topological quantum computation.This thesis mainly introduce our experiments on the basis of bosonic 87Rb and quantum fermionic 40K, including achieved a light-induced vector gauge potential using 1064 nm optical-dipole-trap lasers; Report the first experimental realization and investigation of a spin-orbit coupled Fermi gas; Experimentally and theoretically radio-frequency spectroscopy and pairing of a spin-orbit coupled Fermi gas; Demonstrate a dynamic process in which spin-orbit coupling coherently produces s-wave Feshbach molecules from a fully polarized Fermi gas; Experimentally measured with the momentum-resolved Raman spectroscopy; use laser light near resonant with a molecular bound-to-bound transition to control a magnetic Feshbach resonance in ultracold Fermi gases.Synthetic gauge fields make the neutral atoms behave as charged particles in a magnetic field, so we could simulate charged particles with cold atoms. Using two crossed 1064 nm optical-dipole-trap lasers to be the Raman beams, an effective vector gauge potential for Bose-Einstein condensed 87Rb is experimentally created. The atoms at the far detuning of the Raman coupling are loaded adiabatically into the dressed states by ramping the homogeneous bias magnetic field with different paths and the dressed states with different energies are studied experimentally. We experimental realization of a SO coupled degenerate Fermi gas with 773 nm lasers, and the main results include the following:Spin dynamics, spin-resolved momentum distribution, momentum distribution, the change of fermion population, map out single particle dispersion.Experimentally, the integrated spectroscopy is measured, showing characteristic blue and red shifts in the atomic and molecular responses, respectively, with increasing spin-orbit coupling. Theoretically, a smooth transition from atomic to molecular responses in the momentum-resolved spectroscopy is predicted, with a clear signature of anisotropic pairing at and below resonance. Our many-body prediction agrees qualitatively well with the observed spectroscopy near the Feshbach resonance.We demonstrate a dynamic process in which spin-orbit coupling coherently produces s-wave Feshbach molecules from a fully polarized Fermi gas, and induces a coherent oscillation between these two. This demonstrates experimentally that spin-orbit coupling does coherently couple singlet and triplet states, and implies that the bound pairs of this system have a triplet p-wave component, which can become a topological superfluid by further cooling to condensation and confinement to one dimension.Raman spectroscopy has several significant advantages comparing with RF spectroscopy. The bound molecules can be directly observed and the binding energy can be simultaneously determined in a single running experiment. The energy-momentum dispersion spectra of the ultracold Fermi gas in the BEC side are measured and reconstructed.We experimentally investigate magnetic Feshbach resonance in combination with laser light and characterize the laser-modified bound state by using rf spectroscopy. The spectrum of excited molecular states is measured by applying a laser field that couples the ground Feshbach molecular state to electronically excited molecular states. Nine strong bound-to-bound resonances are observed. We use radio-frequency spectroscopy to characterize the laser-dressed bound state near a specific bound-to-bound resonance and show clearly the shift of the magnetic Feshbach resonance using light.