Strongly correlated quantum matter underlies many grand challenges of many-body physics. Canonical examples of this include hydrodynamic quark-gluon plasmas, high-TC superconductors, and neutron stars. Ultracold atoms in optical potentials provide ideal model systems where the Hamiltonian is precisely known and relevant parameters such as the interaction strength, temperature, and even quantum statistics can be controlled in a pristine fashion.

In this talk, I will present a broad range of experiments with ultracold atoms in optical potentials, ranging from fundamental tests of quantum mechanics, to the basic building block of a noisy intermediate scale quantum (NISQ) computing platform, to probing emergent quasiparticles in a strongly interacting Bose-Fermi mixture.

Using a novel implementation of state-dependent transport, I will demonstrate a rigorous test of the superposition principle by coherently delocalizing single atoms over large distances in quantum random walks. Based on these techniques, I will present the basic building block of a scalable boson sampling machine, by revealing the Hong-Ou-Mandel interference of two indistinguishable bosonic atoms. Such a machine holds promise to soon provide a speedup of quantum over classical devices. 

Furthermore, I will present a recent experiment on an archetypal quasiparticle, the Bose polaron. For example, in solids, Bose polarons form when moving electrons polarize the surrounding ionic crystal lattice. I will demonstrate that immersing fermionic impurity atoms into a dense quantum gas – a Bose Einstein condensate – realizes an ideal testbed to probe the fate of the Bose polaron at strong interactions.