Excitons are being explored in materials science and information technology as a means of storing light. These luminous quasiparticles move through individual layers of quantum materials and can absorb and emit light with high efficiency. They form when a laser pulse excites an electron, leaving behind a positively charged "hole." The electron and hole attract each other and behave together like a new, independent particle. When the quasiparticle recombines, it emits light and can be detected in high-tech laboratories.