Collective Excitonic Assembly in Perovskite Superlattice

Abstract Perovskites exhibit remarkable attributes that make them highly suitable for photovoltaics and multiparameter optical emitters. These benefits arise from their high oscillator strength, excellent solar absorption, and superior charge transport properties. Exploring many‐body quantum states in perovskites offers a promising path to advance their applications from conventional optoelectronic materials to cutting‐edge ultrafast quantum operations–a dynamic area of research. Researchers have observed significant transitions from superfluorescence (SF) to cavity‐enhanced superfluorescence (CESF) when coupled with the whispering gallery mode. Here, the formation of a collaborative quantum state of excitons within a quantum dot ensemble using lead halide perovskite is demonstrated, exhibiting both SF and CESF. The findings show that the cavity enhances the coherence time of collective excitons by nearly threefold. However, coherence in CESF is more vulnerable to external light fields, particularly when using a second beam as a perturbation in time‐resolved spectroscopy. The coherence rebuilding time occurs on a remarkably short timescale of 8 ps. Under CESF conditions, stimulated radiation produces highly linearly polarized emissions up to which can be maintained for over 10 ps. In contrast, such polarization is negligible in SF. These results underscore the potential for applications in ultrafast, photoelectric compatible quantum devices using perovskite‐based superlattices.