Mattiotti Francesco, Kuno Masaru, Borgonovi Fausto, Jankó Boldizsár, Celardo G Luca
Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556, United States.
Dipartimento di Matematica e Fisica and Interdisciplinary Laboratories for Advanced Materials Physics, Università Cattolica del Sacro Cuore, Brescia 25121, Italy.
Nano Lett. 2020 Oct 14;20(10):7382-7388. doi: 10.1021/acs.nanolett.0c02784. Epub 2020 Sep 29.
Recent experiments by Rainò et al. ( 2018, 563, 671-675) have documented cooperative emission from CsPbBr nanocrystal superlattices, exhibiting the hallmarks of low-temperature superradiance. In particular, the optical response is coherent and the radiative decay rate is increased by a factor of 3, relative to that of individual nanocrystals. However, the increase is 6 orders of magnitude smaller than what is theoretically expected from the superradiance of large assemblies, consisting of 10-10 interacting nanocrystals. Here, we develop a theoretical model of superradiance for such systems and show that thermal decoherence is largely responsible for the drastic reduction of the radiative decay rate in nanocrystal superlattices. Our theoretical approach explains the experimental results ( 2018, 563, 671-675), provides insight into the design of small nanocrystal superlattices, and shows a 4 orders of magnitude enhancement in superradiant response. These quantitative predictions pave the path toward observing superradiance at higher temperatures.
拉伊诺等人（2018年，第563卷，第671 - 675页）最近的实验记录了CsPbBr纳米晶体超晶格的协同发射，展现出低温超辐射的特征。特别是，光学响应是相干的，并且相对于单个纳米晶体，辐射衰减率提高了3倍。然而，这种提高比由10¹⁰个相互作用的纳米晶体组成的大型组件超辐射理论预期值小6个数量级。在此，我们针对此类系统开发了一种超辐射理论模型，并表明热退相干在很大程度上导致了纳米晶体超晶格中辐射衰减率的大幅降低。我们的理论方法解释了实验结果（2018年，第563卷，第671 - 675页），为小型纳米晶体超晶格的设计提供了见解，并显示出超辐射响应增强了4个数量级。这些定量预测为在更高温度下观测超辐射铺平了道路。
