Single-atom-resolved detection of ultracold atoms in optical lattices using quantum-gas microscopes has enabled a new generation of experiments in the field of quantum simulation. While such devices have been realised with bosonic species, a fermionic quantum-gas microscope has proven more challenging. We recently demonstrated single-site- and single-atom-resolved florescence imaging of fermionic potassium-40 atoms in a quantum-gas microscope setup using electromagnetically-induced-transparency cooling . We detected on average 1000 fluorescence photons from each single atom within 1.5 s, while keeping them close to the vibrational ground state of the optical lattice.
Our fermionic quantum-gas microscope will provide the possibility to probe quantities that are difficult to access directly, such as spin-spin-correlation functions or string-order. It would allow the study of out-of-equilibrium dynamics, the spreading of correlations and the build-up of entanglement in many-particle fermionic quantum systems. It could perform quantum simulation of the Fermi-Hubbard model, which is conjectured to capture the key mechanism behind high-temperature superconductors.
 E. Haller, J. Hudson, A. Kelly, D. Cotta, B. Peaudecerf, G. D. Bruce, and S. Kuhr, Single-atom imaging of fermions in a quantum-gas microscope, Nature Physics 11, 738-742 (2015)