Study Of Photoassociation For¹S₀-¹P₁Transition Of Cold Ytterbium Atoms

The frequency uncertainty of neutral atom optical clock is superior to the current timing cesium (Cs) atomic clock, expected to become candidates for next frequency standard. After eliminated the first-order Doppler shift and recoil frequency shift, collision frequency shift and blackbody radiation frequency shift are the two main factors that affect the frequency uncertainty. If we trap one atom on each grid point of three-dimensional optical lattice, the collision frequency shift effect of the atom optical clock can be virtually eliminated. This paper will focus on the collision atom optical clock frequency shift, we will take advantage of the collisional effect of the photoassociation, thereby reducing collision frequency shift in atomic optical clock. The process of photoassociation is under the action of two cold atoms in ground state collide with each other, absorbing a red detuned resonance PA laser (PA) photon, the formatted excited states molecules escaped after spontaneous emission. As a result, there is only zero or one atom on each grid point in the optical lattice, reduced the collision between the atoms in the lattice point. We analyzed the physical mechanism of photoassociation to the formation of ultracold molecules, analyze the impact of molecular formation rate on light intensity、detuning、cold atomic sample density and temperature. The stark effect generated by optical lattice laser will affect ’S0-1P1photoassociation transition, this paper also give detailed theoretical calculations of magic wavelength in optical lattice for the photoassociation process. In addition, the399-nm photoassociation light in experiment is generated using quadratic nonlinear effects of nonlinear crystal (LBO). By frequency doubling798-nm semiconductor laser in ring cavity, combined polarization frequency stabilization to obtain a stable399-nm laser output. All above work will be ready for the next step to carry out the ytterbium atomic photoassociation experiment.