2D-QuEST · Chemical Structure, Photo Physics and Emission Control of Single-Photon Emitters in Two-Dimensional Materials

Chemical Structure, Photo Physics and Emission Control of Single-Photon Emitters in Two-Dimensional Materials

Single-photon sources are the foundation of quantum optical technologies. Since the first demonstration of single-photon emission from sodium atoms in 1977, this nonclassical phenomenon has been observed in various types of solid-state zero-dimensional and one-dimensional materials. Recently, a new class of single-photon emitter has emerged based on atomically thin two-dimensional (2D) materials, such as semiconducting transition metal dichalcogenides and hexagonal boron nitride (hBN) monolayers. These novel single-photon emitters are due to the generation and recombination of electron-hole pairs (excitons) that are spatially localized by natural defects in 2D materials. Thosee defects can be located at desired positions with atomic precision suggesting the potential to build extended quantum emitter networks. The promising properties offer a new path to the scalable integration of high-quality quantum emitters in quantum optical technologies. However, the research of 2D quantum emitters (2DQEs) is just at an early stage with many open questions about their fundamental properties. The overall objectives of the project comprise two parts: Firstly, to develop a better understanding of the chemical and electronic structure of the defects in 2D materials. Secondly, to explore controlling the single photon emission for quantum optics applications. Our results suggests at least two types of hBN defects with different chemical structures and different bandgap, can be selectively excited with different laser frequency and emits single photons. To explore the control of single photon emission, this project has developed a compact solid immersion metalens to collect emission from dipole emission centers, with high collection efficiency which is independent on the dipole orientations. In additions, this project has developed an efficient way to largely enhance the fluorescence of quantum emitter with broadband response by coupling the quantum emitters to plasmonic waveguide. Finally, the project has developed a novel efficient frequency domain technique to measure the spectrally resolved fluorescence lifetime of quantum emitters in the microsecond to millisecond time range, which is hardly achieved by the existing fluorescence lifetime methods.

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