Perovskites—compounds with the CaTiO 3 -type crystal structure—show outstanding performance in photovoltaics and multiparameter optical emitters due to their large oscillator strength, strong solar absorption, and excellent charge-transport properties. However, the ability to realize and control many-body quantum states in perovskites, which would extend their application from classical optoelectronic materials to ultrafast quantum operation, remains an open research topic. Here, we generate a cooperative quantum state of excitons in a quantum dot ensemble based on a lead halide perovskite, and we control the ultrafast radiation of excitonic quantum ensembles by introducing optical microcavites. The stimulated radiation of excitonic quantum ensemble in a superlattice microcavity is demonstrated to not be limited by the classical population-inversion condition, leading to a picosecond radiative duration time to dissipate all of the in-phase dipoles. Such a perovskite-assembly superlattice microcavity with a tunable radiation rate promises potential applications in ultrafast, photoelectric-compatible quantum processors.
Efficient and fast scintillators are in high demand in a variety of fields, such as medical diagnostics, scientific instruments and high-energy physics. However, the trade-off between high scintillation efficiency and fast timing properties is a common challenge facing almost all scintillators. To overcome this limitation, we have developed a strategy for organic scintillators by directing all hot excitons into fast singlet emission states without involving the lowest triplet states. Our scintillator, 1,1,2,2-tetrakis(4-bromophenyl)ethylene, shows an ultrafast radiative lifetime of 1.79 ns and a light yield of ∼ 34,600 photons per MeV, exhibiting an excellent combination of high light yield and short decay time. Our work provides a method to design efficient and ultrafast scintillators, and paves the way towards exciting applications for ultrafast detection and imaging.