Superfluorescent emission from a discharge-excited rare-gas halide system

Masaaki Ashida, Ariyuki Kato, Osamu Morikawa +1 more

James Clemens, H. J. Carmichael

Ajay K. Poonia, Barnali Mondal, Matthew C. Beard +2 more

Superfluorescence, a cooperative coherent spontaneous emission, is of great importance to the understanding of many-body correlation in optical processes. Even though superfluorescence has been demonstrated in many diverse systems, it is hard to observe in electron-hole plasma (EHP) due to its rapid dephasing and hence needs strong magnetic fields or complex microcavities. Herein, we report the first experimental observation of superfluorescence from EHP up to a moderate temperature of 175 K without external stimuli in a coupled metal halide perovskite quantum dots film. The EHP exhibits macroscopic quantum coherence through spontaneous synchronization. The coherence of the excited state decays by superfluorescence, which is redshifted 40 meV from the spontaneous emission with a ∼1700 times faster decay rate and exhibits quadratic fluence dependence. Notably, the excited state population's delayed growth and abrupt decay, which are strongly influenced by the pump fluence and the Burnham-Chiao ringing, are the characteristics of the superfluorescence. Our findings will open up a new frontier for cooperative emission and light beam-based technologies.

A. V. Andreev, N. A. Enaki, Yu A Il'inskiĭ

Yue Tang, Annalisa Bruno, Gerald Ong +9 more

Metal halide perovskites (MHPs) have emerged as promising platforms for cooperative quantum emission. Superfluorescence is particularly intriguing because it arises from spontaneous synchronization of initially incoherent emitters into a macroscopic quantum state, producing delayed, intense, ultrafast bursts of coherent light. While superfluorescence has been demonstrated in perovskite nanocrystal superlattices and thin films, the mechanisms that enable its emergence at elevated temperatures, and the boundaries that separate cooperative from non-cooperative emission regimes, remain insufficiently understood.[1],[2] Addressing these knowledge gaps is essential for advancing superfluorescence toward quantum photonic applications.[3] In this talk, I present how our work tackles the challenges of identifying, and controlling superfluorescence in quasi-2D perovskite thin films. We demonstrate clear evidence to distinguish superfluorescence from amplified spontaneous emission and spontaneous emission. A comprehensive experimental phase map is constructed to reveal when and how macroscopic coherence forms, how it decays, and under what conditions it transitions into non-cooperative regimes.[4] Using quasi-2D PBA:CsPbBr3 thin films, we demonstrate superfluorescence with the lowest threshold fluence reported at 78 K in metal halide perovskites. Temperature and fluence dependent steady state and ultrafast spectroscopies resolve cooperative emission from 78 to 180 K, including a sharper coupled emission band, a delayed emission peak, ultrafast radiative lifetimes, quadratic like intensity scaling, and Burnham-Chiao ringing. We also map a phase diagram that delineates spontaneous emission, superfluorescence, and amplified spontaneous emission, and we observe deviations from ideal superfluorescence at high fluences and elevated temperatures, reflecting competing many-body and dephasing processes.[4] To interpret these observations, we introduce the ab initio quantum model Superfluorescence Non-Approximating Integrating Large Solver (SNAILS), which tracks emission density, inter emitter correlations, excited state populations, and trace distance under varying pumping and dephasing conditions.[4] Simulations reproduce delayed cooperative bursts when dephasing is weak and show rapid suppression of correlations and loss of delay when dephasing is stronger. Trace distance dynamics identify synchronization plateaus during cooperative emission and prolonged plateaus linked to subradiant or dark states under high dephasing, establishing a unified framework for cooperative emission and its breakdown in perovskite thin films. Overall, this work clarifies the optical and dynamical conditions required for macroscopic coherence in perovskites. The combined insights from phase mapping, ultrafast spectroscopy, and quantum modeling highlight strategies for lowering threshold fluence, mitigating dephasing, and extending superfluorescence toward higher temperatures.

Arnab Ghosh, Patrick Brosseau, Dmitry N. Dirin +2 more

Superfluorescence, the cooperative burst of spontaneous emission from an ensemble of dipoles, arises when microscopic oscillators spontaneously synchronize their phases. Here we show that this process can be reversed in time within quantum materials. Coherent multidimensional spectroscopy of halide perovskite quantum dots reveals a delayed cooperative absorption burst, the mirror image of superfluorescent emission, driven by transient polaron fields that phase-lock unit-cell dipoles within 100 fs. The effect scales systematically with quantum-dot size and halide composition, reaching near-unity coherence fidelity even at 300 K. A microscopic exciton-polaron model reproduces the buildup and decay of the coherent state, identifying lattice polarons as the mediators of synchronization. These results demonstrate that many-body temporal coherence can self-organize and persist at room temperature, opening routes toward engineered collective optical states and superabsorbing quantum devices.