In new research appearing in Physical Review Letters, an international research team, including UC Davis physicists, has expanded the Fermi-Hubbard model, allowing for a more detailed exploration of materials and their properties. In the study, the researchers measured the equation of state for Ytterbium atoms in an optical lattice. Specifically, they used the fermionic isotope 173Yb, which is a metallic element with atoms that can adopt six possible states.