Interaction induced point scatterer lattices and flat band condensation of exciton-polaritons

One of the recently established paradigms in the study of condensed matter physics is examining a system's behaviour in artificially constructed potentials. This allows one to obtain insight on a range of physical phenomena which may require non-feasible or hardly achievable experimental conditions. Here, we devise and implement an all-optical approach to a system of exciton-polaritons in semiconductor microcavities to load the particles into desired periodic potentials. We demonstrate a two-dimensional system of polariton condensates in two regimes - lattices of point scatterers, and confined states through non-resonant pumping with Gaussian beams arranged in a conventional, and an inverse Lieb configuration. We utilize energy tomography on the coherent polariton emission to reveal the intricate band structure of polaritonic Lieb lattices, and report on fully optically generated polariton condensation in S-, and dispersionless P-band states.