Strong coupling regime and bound states in the continuum between a quantum emitter and phonon-polariton modes

We investigate the population dynamics of a two-level quantum emitter (QE) placed near a hexagonal boron nitride (h-BN) layer. The h-BN layer supports two energy phonon-polariton bands. In the case that the transition energy of the QE is resonant to them, its relaxation rate is enhanced several orders of magnitude compared to its free-space value and the population of the QE excited state shows reversible dynamics. We further show that for specific parameters of the QE/h-BN layer system, the QE population can be trapped in the excited state, keeping a constant value over long periods of time, thus demonstrating that the h-BN layer is a platform that can provide the strong light-matter interaction conditions needed for the formation of bound states in the electromagnetic continuum of modes. Semi-analytical methods are employed for determining whether such a bound state can be formed for given coupling conditions, as well as for computing the amount of initial population trapped in it. The bound states in the continuum are important for designing practical future quantum applications. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

The population dynamics of a two-level quantum emitter (QE) near a hexagonal boron nitride (h-BN) layer were investigated in this study. It was found that the relaxation rate of the QE is significantly enhanced when resonant with the phonon-polariton bands of the h-BN layer, leading to reversible dynamics and potential formation of bound states. Such bound states in the continuum are crucial for designing practical future quantum applications.