QLunch: Bhavik Kumar

Speaker: Bhavik Kumar

Title: Estimating applied potentials in cold atom lattice simulators

Abstract: Cold atoms in optical lattices provide a versatile and highly controllable platform for quantum simulation, enabling the realization of a wide class of Hubbard models together with site-resolved readout via quantum gas microscopes. In principle, these systems also allow for the implementation of arbitrary site-dependent potentials. In practice, however, accurately applying and calibrating such potentials remains challenging, as lattice spacings are typically below the optical diffraction limit. In this talk, I will present a simple and efficient experimental protocol for precisely estimating site-resolved potentials in optical lattice simulators. The key ingredient is the ability, available for several atomic species, to switch off interactions using a Feshbach resonance, rendering the dynamics effectively non-interacting and therefore classically tractable. We show that time-resolved snapshots of the evolution of a known and easily prepared initial state are sufficient to reconstruct the underlying potential with high accuracy. The protocol is robust against state preparation errors and uncertainties in the hopping rate. Finally, I will discuss how this approach can be incorporated into a recent Gaussian tomography protocol based on randomized measurements in cold-atom quantum simulators. Based on joint work with Daniel Malz.