Unveiling the Enhancement of Spontaneous Emission at Exceptional Points

Exceptional points (EPs), singularities of non-Hermitian physics where complex spectral resonances degenerate, are one of the most exotic features of nonequilibrium open systems with unique properties. For instance, the emission rate of quantum emitters placed near resonators with EPs is enhanced (compared to the free-space emission rate) by a factor that scales quadratically with the resonance quality factor. Here, we verify the theory of spontaneous emission at EPs by measuring photoluminescence from photonic-crystal slabs that are embedded with a high-quantum-yield active material. While our experimental results verify the theoretically predicted enhancement, they also highlight the practical limitations on the enhancement due to material loss. Our designed structures can be used in applications that require enhanced and controlled emission, such as quantum sensing and imaging. Published version This work was partly funded by the French National Research Agency (ANR) under the Project POPEYE (Project No. ANR-17-CE24-0020) and the IDEXLYON from Universite de Lyon, Scientific Breakthrough project TORE within the Programme Investissements d Avenir (Project No. ANR-19-IDEX-0005) . It is also supported by the Auvergne-Rhne-Alpes region in the framework of PAI2020 and the Vingroup Innovation Foundation (VINIF) annual research grant program under Project No. VINIF.2021.DA00169. Q. X. gratefully acknowledges the funding support from National Natural Science Foundation of China (Grant No. 12020101003) and a Tsinghua University start-up grant.