Polariton condensation with lead halide perovskite nanocrystals

Abstract

By embedding optically active materials with high oscillator strength in optical microcavities, the strong light-matter interaction regime can be reached where exciton-polariton quasiparticles are formed that are part photon and part exciton. At sufficiently high excitation density, eventually a non-equilibrium Bose-Einstein condensate can form, exhibiting nonlinear behavior, macroscopic coherence and quantum fluid properties. Bulk crystalline thin films of CsPbBr3 in microcavities have shown to allow room temperature polariton condensation. Nanocrystals have the promise of enhanced polariton interactions due to their spatial confinement. Here we report on strong light-matter coupling of colloidal CsPbBr3 nanocrystals and polariton condensation at ambient conditions, as evidenced by nonlinearly increasing emission, line narrowing and coherence measurements. We use a tunable open microcavity based on distributed Bragg reflectors to tune the polariton energy. By precise nanofabrication, we create tiny indentations in the mirrors to effectively produce potential landscapes for the polariton condensate, which opens perspectives to use the polariton quantum fluid as analogue simulator for interesting hamiltonians.