Polariton condensation in <i>S</i>- and <i>P</i>-flatbands in a two-dimensional Lieb lattice

We study the condensation of exciton-polaritons in a two-dimensional Lieb lattice of micropillars. We show selective polariton condensation into the flatbands formed by S and Px,y orbital modes of the micropillars under non-resonant laser excitation.The real space mode patterns of these condensates are accurately reproduced bythe calculation of related Bloch modes of S- and P-flatbands. Our work emphasizes the potential of exciton-polariton lattices to emulate Hamiltonians of advanced potential landscapes. Furthermore, the obtained results provide a deeper inside into the physics of flatbands known mostly within the tight-binding limit