Nature Physics ( IF 19.256 ) Pub Date : 2020-01-13 , DOI: 10.1038/s41567-019-0764-5 Rui Su; Sanjib Ghosh; Jun Wang; Sheng Liu; Carole Diederichs; Timothy C. H. Liew; Qihua Xiong
Exciton polaritons, with extremely low effective mass1, are regarded as promising candidates to realize Bose–Einstein condensation in lattices for quantum simulations2 towards room-temperature operations3,4,5,6,7,8. Along with the condensation, an efficient exciton polariton quantum simulator9 would require a strong lattice with robust polariton trapping as well as strong intersite coupling to allow coherent quantum motion of polaritons within the lattice. A strong lattice can be characterized with a larger forbidden bandgap opening and a larger lattice bandwidth compared with the linewidth. However, exciton polaritons in such strong lattices have only been shown to condense at cryogenic temperatures3,4,5,6,7,8. Here, we report the observation of non-equilibrium exciton polariton condensation in a one-dimensional strong lead halide perovskite lattice at room temperature. Modulated by deep periodic potentials, the strong lead halide perovskite lattice exhibits a large forbidden bandgap opening up to 13.3 meV and a lattice band up to 8.5 meV wide, which are at least 10 times larger than previous systems. Above a critical density, we observe polariton condensation into py orbital states with long-range spatial coherence at room temperature. Our result opens the route to the implementation of polariton condensates in quantum simulators at room temperature.