Superfluorescent phase transition in hybrid perovskites: critical temperature and density

Macroscopic quantum effects such as superconductivity, superfluidity, and Bose-Einstein condensation emerge due to the collective coherence of quantum particles. For electronic phase transitions in solids, thermal processes such as random electron-phonon scattering cause dephasing and limit these phenomena to low temperatures. We recently observed superfluorescence in lead halide perovskite thin films at unprecedentedly high temperatures. In superfluorescence, optically excited dipoles synchronize and reach a collectively coherent quantum state. The resulting giant dipole emits a burst of photons. Similar to other macroscopic quantum effects, superfluorescence also requires robust coherence. Hence, the observation of this collective quantum optical effect at high temperatures provides an unprecedented opportunity for the investigation of mechanisms that enable high-temperature collective quantum states in solids. In this presentation, I will discuss our analysis of system-bath interactions that stabilize macroscopic coherence in superfluorescence in perovskites. Our work provides important insights into the design and development of quantum materials for practical applications