Abstract:

Quantum gas microscopy of two-component fermions trapped in optical lattice is currently shedding new lights on the interplay between doping and magnetism, relevant to high-temperature superconductivity, with for example the recent observations of antiferromagnetism, magnetic polarons and pseudogap. Alkaline-earth atoms offer the perspective to extend the study of the Fermi-Hubbard model to the N-component case, with N up to 10 for strontium, whose phase diagram is vastly unknown. Quantum gas microscopy of N-component fermions remains however still an outstanding experimental challenge.

In the first part of this talk I will report on our novel approach to single atom and spin-resolved imaging of SU(N) fermions. It allows to image individual strontium atoms with a fidelity of $99.5\%$ in only 13 $\$mu s$ as well as the detection of currently up to four nuclear spin states using an optical Stern-Gerlach scheme.

In the second part of this talk I will discuss a recent study of the dynamics impurities in a trapped two-dimensional Bose gas.

We use radiofrequency to transfer a small fraction of impurities in a quasi-2d quantum degenerate Bose gas of $^39$K and track in situ the subsequent dynamics for various repulsive impurity-bath interaction strengths. We observe remarkably slow impurity dynamics above the speed of sound which is captured by taking into account radiation of excitations in the bath. From the time-dependence of the most probable impurity position the drag force above the critical speed is extracted in qualitative agreement with Bogoliubov predictions for heavy impurities.