Quantum gas microscopy and AC conductivity of the 3D Fermi-Hubbard Model

We report our recent experimental measurements on quantum degenerate fermionic 40K atoms in 3D optical lattices for quantum simulation of the Hubbard model. Single-site resolution is achieved via a combined Raman-side band cooling (RSC) and electromagnetically induced transparency (EIT) and a high NA objective. Separate planes in the cubic lattice potential are spectroscopically selected and simultaneously imaged. We probe dissipation by measuring the AC conductivity spectrum in response to an oscillatory force provided by a periodically displaced optical potential. Inter-particle collisional rates are tuned by using an s-wave Feshbach resonance; larger rates manifest as spectral broadening in the conductivity. By operating sufficiently close to the resonance, we leave the perturbative regime in interaction strength. These measurements provide insights into dissipation in non-conventional metals; future directions include investigating transport in excited bands, highly-correlated insulating states, and superfluids.