Fast thermal dephasing limits macroscopic quantum phenomena to cryogenic conditions and hinders their utilization at ambient temperatures. For electronic excitations in condensed media, dephasing is mediated by thermal lattice motion. Therefore, taming the lattice influence is essential for creating collective electronic quantum states at high temperatures.

Here, intensity fluctuations were studied in the macroscopic polarization during the emergence of superfluorescence in a lead-halide perovskite and showed that spontaneously synchronized polaronic lattice oscillations accompany collective electronic dipole emission. An effective field model was developed and theoretically confirmed that exciton lattice interactions lead to a new electronically and structurally entangled coherent extended polaronic state beyond a critical polaron density.

This study established fundamental connections between the transient superfluorescence process observed after the impulsive excitation of perovskites and general equilibrium phase transitions achieved by thermal cooling. By identifying various electron lattice interactions in perovskite structure and their respective role in creating collectively coherent electronic effects in solids, this work provides unprecedented insight into the design and development of new materials that exhibit high temperature macroscopic quantum phenomena.