Formation of matter-wave polaritons in an optical lattice

The polariton is a quasiparticle formed by strong light-matter coupling. It has been exploited to achieve superfluids of light as well as strongly correlated phases in photonic quantum systems. Recently, we have implemented an ultracold-atom polariton analog, where light and matter are replaced by matter waves and excitations in an optical lattice [1, 2]. In our tunable and dissipation-free system, we have spectroscopically accessed the polariton band structure and studied transport behavior in the superfluid and Mott-insulating regimes. Our work opens up novel possibilities for exploring exciton-polariton physics and polaritonic quantum matter.