# Room‐Temperature Collective Quantum Emission Mediated by Wannier–Mott Excitons in CsPbBr3 Nanowires

## TL;DR

Researchers observed room-temperature collective quantum emission in CsPbBr3 nanowires, offering a new way to generate coherent light at ambient conditions.

## Contribution

The study demonstrates superfluorescence in CsPbBr3 nanowires using Wannier–Mott excitons and directional dipole alignment.

## Key findings

- Superfluorescence confirmed by photon bunching, coherence time of ~88 fs, and low excitation threshold.
- Bandgap renormalization and exciton-phonon coupling observed via ultrafast spectroscopy.
- Coherent emission achieved without high excitation densities or complex structural ordering.

## Abstract

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 g
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.

Room‐temperature collective quantum emission emerges in partially aligned CsPbBr3 nanowires through spontaneous synchronization of Wannier–Mott excitons. This alignment enables cooperative dipole–dipole interactions that result in coherent photon bursts (N2 × hν), even under ambient conditions. The emission shows clear superfluorescent signatures including threshold behavior, polarization anisotropy, and sub‐nanosecond temporal bunching.© 2025 WILEY‐VCH GmbH