Ultracold quantum gases in optical lattices provide a unique platform for the study of tailored many-body systems. The realization of quantum gas microscopes marked a new era in this field. They enabled the precision detection of single atoms on individual lattice sites and with this provide direct experimental access to non-local correlation functions. Here we summarize the experimental progress with this new platform, where experiments evolved from textbook like studies in conceptually simple settings towards precisely controlled studies in computationally inaccessible regimes. We discuss recent results on many-body localization in two dimensions as well as on string correlations in Fermi-Hubbard chains.
Reaching dual superfluidity in helium mixtures has long been one of low-temperature physics holy grails . However, this long sought goal has been thwarted by the repulsive interactions between the two isotopes that leads to their demixion at low temperature. In ultracold atoms, the possibility offered by Feshbach resonances of tuning the strength of interatomic interactions has allowed us to cool a mixture of 6Li and 7Li into a regime where the mixture is stable and both species are superfluid. We have proved their superfluid behaviour by creating a counterflow between the two species. We have demonstrated the existence suggesting the existence of a novel damping mechanism generalizing Landau's scenario to superfluid mixtures.
More recently, we have shown that probing the inelastic decay of the mixture could be used as a quantitative probe of the short range correlation of a many-body system.