Implementation of a Quantum Gas Microscope for Fermions

We discuss the technical development of a quantum gas microscope for $^{40}$K. We load a degenerate Fermi gas into a cubic optical lattice of period 527\,nm, which is capable of simulating the Fermi-Hubbard model. The sample is prepared in UHV below a 200\,$\mu$m-thick sapphire window, at the focus of a 5\,mm focal length objective located outside the chamber. To isolate a single plane for imaging, we perform spectroscopic selection in a 210\,G/cm gradient, which separates the hyperfine transition frequencies of adjacent vertical planes by 28\,kHz. We actively suppress variations in the transition frequency due to fluctuations in the ambient magnetic field to less than 3\,kHz via a feed-forward stabilization system. EIT cooling on the 770.1\,nm D$_1$ transition facilitates fluorescence imaging of our atoms with long exposures. Atoms remain pinned in a 200\,$\mu$K-deep lattice, with a $1/e$ lifetime of $67(9)\,\rm{s}$, while scattering $\sim 10^3$ photons per second. Collection of fluorescence photons onto an EMCCD via a 0.8\,NA objective results in a PSF of FHWM 600\,nm, and 94(2)\% of atoms identified in the first frame remain pinned in successive frames, enabling reconstruction of the lattice-site occupancy. We present ongoing progress in obtaining lower entropy samples.