Room‐Temperature Collective Quantum Emission Mediated by Wannier–Mott Excitons in CsPbBr ₃ Nanowires

Room-temperature collective quantum emission (RT-CQE), enabled by many-body interactions and phase-synchronized dipole oscillations, offers a promising path for scalable quantum photonics. Here, superfluorescence (SF) is demonstrated in CsPbBr₃ perovskite nanowires (NWs), facilitated by Wannier-Mott excitons with spatially delocalized wavefunctions and strong dipole-dipole interactions. The intrinsic quasi-1D geometry and occasional bundling promote preferential dipole alignment along the NW axis, enabling long-range phase coherence. Key experimental signatures, photon bunching with <i>g</i> ²(0) ≈2, femtosecond-scale coherence time (≈88 fs), and ultralow excitation threshold (≈210 nJ^-1 cm²), confirm the onset of SF at ambient conditions. Ultrafast spectroscopy reveals bandgap renormalization, state filling, and exciton-phonon coupling, consistent with collective excitonic behavior mediated by delocalized states. Unlike other RT-SF mechanisms based on polarons or electron-hole liquids, the system exploits directional dipole alignment and exciton delocalization in quasi-1D NWs, allowing coherent emission without the need for high excitation densities or complex structural ordering. These findings demonstrate that CsPbBr₃ NWs can sustain RT-SF driven by exciton delocalization and directional dipole coupling, providing a new physical platform for coherent light generation under ambient conditions.