Generation of Degenerate Quantum Gases of Ytterbium Atoms

Abstract

Ytterbium atoms have taken attraction from the scientists owing to their distinct properties compared with alkali atoms. ytterbium atoms have the intercombination transtion and clock transitions that allows to study precise controls of interatomic interaction and new standard of time. In 2003, Takahashi group rst achieved the Bose-Einstein condensate (BEC) of 174Yb following degenerate fermi gases (DFG) of 171Yb and 173Yb atoms. After these achievements, ytterbium becomes a new candidate for the quantum simulators, especially SU(N) symmetry using 173Yb atoms. Also, It attracts the quantum computer using their clock transition. This thesis presents two topics. First topic is the experimental apparatus for the degenerate quantum gases of ytterbium atoms. The other is the topic on the precise measurements of optical Feshbach resonances of 174Yb atoms. First of all, we describe our experimental apparatus for generating quantum degenerate gases of bosonic 174Yb and fermionic 173Yb atoms, the rst ultracold gases of ytterbium atoms in South Korea. We use a Zeeman slower to generate a slow atomic beam and collect atoms in a magneto-optical trap formed by 556 nm laser beams without frequency modulations. Laser-cooled ytterbium atoms are transferred to a crossed optical dipole trap and evaporatively cooled to quantum degeneracy. Our system generates a BEC containing over 6 104 174Yb atoms or aDFG of about 7 104 173Yb atoms at T=TF=0.8(1), where TF is the Fermi temperature of the gas. We highlight the high performance of the Zeeman slower and the home-made SHG units for 399 nm and 556 nm lights. Also, we measure the optical Feshbach resonances (OFRs) of four leastbound vibrational levels near the intercombination transition 1S0-3P1 with a pure Bose-Einstein condensate (BEC) of 174Yb atoms. We induce photoassociation (PA) in a 174Yb BEC using the intercombination transition for precise measurements of the OFRs. The dependence of OFRs to PA laser intensities and frequencies are studied and characterized for several least bound vibrational levels. We con rmed our methods by measuring the time evolution of a BEC subjected to a PA beam resonant to the fourth vibrational level from the dissociation limit. A PA spectroscopy with a BEC of 174Yb allows us to have clear spectra because the thermal e ect is suppressed and s-wave scattering dominants.