Low temperatures and dynamical probes in a Fermi-Hubbard quantum simulator

Ultracold fermionic atoms in optical lattices offer faithful realizations of Hubbard models, which are fundamental to modern condensed matter physics. However, quantum simulations have previously been challenged by the low energy scales involved, limiting achievable temperatures. We present a recent breakthrough resulting in a several-fold temperature reduction in such an atomic Hubbard system. This is done by adiabatically transforming a low-entropy band insulator into a strongly correlated final state. What was once a challenge is now an opportunity: the low energy scales in these simulations allow us to directly observe dynamics that typically must be inferred indirectly—only now at temperatures physically relevant for materials. By driving the system and measuring heating with a widely tunable wave vector, we can access the dynamic structure factor across the entire Brillouin zone. Specifically, we measure heating in a novel, data efficient way by ramping our driven state back to a band-insulator and counting defects. Using site-resolved microscopy, we also measure the real and imaginary parts of the response by studying correlations under the drive. This work directly demonstrates the utility of quantum simulation in addressing open problems in correlated electron physics.