We report a high-resolution microscope system for imaging ultracold ytterbium atoms trapped in a two-dimensional optical lattice. By using the ultraviolet strong transition combined with a solid immersion lens and high-resolution optics, our system resolved individual sites in an optical lattice with a 544-nm spacing. Without any cooling mechanism during the imaging process, the deep potential required to contain the atoms was realized using a combination of a shallow ground-state and a deep excited-state potentials. The lifetime and limitations of this setup were studied in detail.

We demonstrate site-resolved imaging of a strongly correlated quantum system without relying on laser-cooling techniques during fluorescence imaging. We observed the formation of Mott shells in the insulating regime and realized thermometry on the atomic cloud. This work proves the feasibility of the noncooled approach and opens the door to extending the detection technology to new atomic species.Comment: 5 pages, 4 figure

We developed a high-power laser system at a wavelength of 399 nm for laser cooling of ytterbium atoms with ultraviolet laser diodes. The system is composed of an external cavity laser diode providing frequency stabilized output at a power of 40 mW and another laser diode for amplifying the laser power up to 220 mW by injection locking. The systematic method for optimization of our injection locking can also be applied to high power light sources at any other wavelengths. Our system, which does not depend on complex nonlinear frequency-doubling, has great importance for implementing transportable optical lattice clocks, and is also useful for investigations on condensed matter physics or quantum information processing using cold atoms.

No abstract

We present an all-optical method to load 174 Yb atoms into a single layer of an optical trap near the surface of a solid immersion lens which improves the numerical aperture of a microscope system. Atoms are transported to a region 20 µm below the surface using a system comprised by three optical dipole traps. The "optical accordion" technique is used to create a condensate and compress the atoms to a width of 120 nm and a distance of 1.8 µm away from the surface. Moreover, we are able to verify that after compression the condensate behaves as a two-dimensional quantum gas.