Superfluorescence from Electron-Hole Plasma at Moderate Temperatures of 175 K

Ajay K. Poonia, Barnali Mondal, Matthew C. Beard, Angshuman Nag, and K. V. Adarsh

Phys. Rev. Lett. 132, 063803 – Published 8 February 2024

Abstract

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 $\sim 1700$ 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.

Received 29 September 2023
Accepted 12 January 2024

DOI:https://doi.org/10.1103/PhysRevLett.132.063803

Physics Subject Headings (PhySH)

Light-matter interaction Photonics Spontaneous emission Ultrafast optics

Atomic, Molecular & Optical

Authors & Affiliations

Ajay K. Poonia¹, Barnali Mondal², Matthew C. Beard³, Angshuman Nag ², and K. V. Adarsh ^1,*

¹Department of Physics, Indian Institute of Science Education and Research, Bhopal-462066, India
²Department of Chemistry, Indian Institute of Science Education and Research, Pune-411008, India
³Chemistry and Nanoscience Science Center, National Renewable Energy Laboratory, Golden, Colorado 80401, USA

^*Corresponding author: adarsh@iiserb.ac.in

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Vol. 132, Iss. 6 — 9 February 2024

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Images

Figure 1
(a) The upper panel figures show the emergence of correlated dipoles from an ensemble of uncorrelated dipoles below a critical temperature ( $T_{SF}$ ) and above a critical number of dipoles ( $N_{SF}$ ). The lower panel’s left figure illustrates the exponential decay of uncorrelated dipoles in the form of ASE and the right figure shows the decay of correlated dipoles through superfluorescence (SF) burst exhibiting the Burnham-Chiao ringing. (b) Color plot of excitation-dependent photoluminescence (PL) of ${CsPbBrI}_{2}$ film, illustrating spontaneous emission (SE) and ASE at low fluences, while the emergence of superfluorescence triggered by a pump fluence exceeding $25 μ J / {cm}^{2}$ . (c) Photoluminescence spectra at various fluences, depicting the transition of spontaneous emission to ASE and the progression from ASE to superfluorescence.
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Figure 2
(a) Color plot of the TA at low fluence ( $4 μ J / {cm}^{2}$ ) reveals the photobleach at the exciton position due to phase-space filling and excited state absorption at higher energy levels. (b) Decay kinetics of the TA photobleach maxima at $4 μ J / {cm}^{2}$ , revealing the exponential decay of carrier recombination corresponding to spontaneous emission and decay kinetics of the superfluorescence regime ( $200 μ J / {cm}^{2}$ ), displaying carrier recombination in the form of bursts. (c) Color plot of the TA at $200 μ J / {cm}^{2}$ , demonstrating the photobleach due to phase-space filling of EHP and superfluorescence (dashed square bracket). (d) spectral slices of the TA at 0.7 ps, highlighting the energy distribution of the filled exciton, EHP states, and the superfluorescence. (e) Time kinetics of the superfluorescence, showcasing the decay in the form of bursts with Burnham-Chiao ringing. (f) Decay time and (g) coherence buildup time of superfluorescence as a function of pump fluence. (h) Time evolution of superfluorescence decay as a function of square root of time in femtoseconds.
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Figure 3
(a) Time kinetics of the TA at 5 K with a pump energy of 3.1 eV, revealing the buildup of photobleaching signals over a duration of 100 ps. (b) Color plot of the excitation-dependent photoluminescence (PL) with a pump energy of 3.1 eV, demonstrating the occurrence of only ASE and absence of superfluorescence. (c) Color plot of the excitation-dependent photoluminescence at 175 K, showing the emergence of superfluorescence. (d) Color plot of the excitation-dependent photoluminescence at 300 K showing the absence of superfluorescence and only ASE.
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