A three-dimensional optical lattice of ytterbium and lithium atomic gas mixture

We develop an optical lattice system for an ultracold atomic gas mixture of ytterbium (¹⁷⁴Yb) and lithium (⁶Li), which is an ideal system for studying disorder and impurity problems. We load a Bose-Einstein condensate of ¹⁷⁴Yb into a three-dimensional optical lattice and observe its interference patterns in time-of-flight (TOF) images. Furthermore, we perform laser spectroscopy of ¹⁷⁴Yb in an optical lattice using the ultranarrow optical transition ¹S₀-³P ₂ in both cases with and without ⁶Li. Owing to the weak interspecies interaction, we do not observe clear effects of ⁶Li in the obtained interference patterns or excitation spectra. However, this is an important first step in the optical control of atomic impurity in ultracold fermions. We also measure the polarizabilities of the ³P₂ state of ¹⁷⁴Yb atoms in an optical trap with a wavelength of 1070 nm. We reveal that the polarizability can be tuned to be positive, zero, or the same as the ground state, which is useful for certain applications.