EAGER: Investigation of local strain and single photon emitters in two-dimensional materials

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Nontechnical description:Single photon emitters (SPEs), which emit light as single particles (photons), are important light sources for leading quantum information technologies, such as computation, communication, and cryptography. To integrate SPEs with miniaturized devices, many researchers focus on solid-state systems because they can be fabricated and controlled precisely using current nanofabrication techniques. In recent years, SPEs have been reported in two-dimensional (2D) materials, which have only nanometer-scale thicknesses. This greatly expands the possibility of scalable integration of SPEs on a chip. However, the color (energy) of emitted photons is difficult to control because the fundamental principles that govern single photon emission in 2D materials are not entirely understood, leading to SPE behavior that may appear to be random. In this project, the research team develops a specially-designed microscopic device patterned with sharp tips to quantitatively determine how the strength and shape of strain, or mechanical deformation, in 2D materials determines or alters the performance of SPEs. In addition, the research team introduces middle-school students to micro-artificial structures, like the one used in this project, by creating a series of short videos explaining fundamental concepts and distributing the videos over a wide range of social media platforms, allowing the research team to reach a large audience. These educational resources introduce middle-school students to topics that are interesting, do not require advanced mathematics to understand, and are generally not included in a middle-school curriculum.Technical description:While SPEs in layered hexagonal boron nitride (hBN) at room temperature take advantage of high photon purity, bright emission, and favorable quantum efficiencies, they exhibit extreme inhomogeneity, emitting photons at random energies spanning a broad range. This limits the suitability of SPEs for applications in quantum information science and technology, such as on-chip integrated quantum photonic circuits. This project will use a specially-designed multi-tip platform to investigate the SPEs with tunable local strain and perform a comprehensive study of the relationship between local strain and SPEs in hBN. The multi-tip platform provides the capability to control strain through careful design of the tip geometry and distribution, opening up opportunities in controllable strain engineering. The research team applies uniaxial, biaxial, and triaxial tensile and/or compressive strain on and around existing SPEs to quantitatively determine the strength and orientation dependence and investigate the fundamental principles that give rise to a variety of emission energies from SPEs. In addition to studying intrinsic SPEs, high strain is intentionally induced to investigate the formation process of SPEs. This project advances the understanding of the relationship between local strain and SPEs in hBN. The multi-tip platform used in this project can be directly extended to other 2D materials to investigate strain-induced light-matter interactions in 2D materials, such as SPEs in transition metal dichalcogenides and pseudo-magnetic fields in graphene, and explore their transport, topological, and quantum behaviors.This project is jointly funded by Electronic and Photonic Materials program in the Division of Materials Research and the Established Program to Stimulate Competitive Research (EPSCoR).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.