Quantum gas microscopy of alkali-earth atoms

Ultracold atoms in optical lattices realize the cleanest “materials” in Nature. By replacing electrons with atoms, and the crystalline structure of solids with defect-free periodic potentials created by interfering laser beams, they allow one to build cornerstone models of condensed-matter physics such as the Hubbard or Heisenberg models from the ground up. Moreover, in these systems the spacing between lattice sites is as large as 500 nm, which allows to image the occupation of every single lattice site with a high numerical aperture optical microscope. This gives access to the fascinating physics of strongly-correlated materials in a novel setting where, compared to solid-state systems, a much larger level of control and completely new microscopic observables become possible. In the strontium lab, we have extended the concept of quantum gas microscopy to an alkali-earth species, which has two valence electrons instead of one. Thanks to this, strontium offers perfect two-level systems, metastable electronic states, ultranarrow clock transitions, and multicomponent fermions with SU(10) interactions: a wealth of new ingredients for quantum simulation and quantum optics experiments.