The light years: Atomic-scale quantum photonics with combined optical and electron microscopy

Pearl Jam’s hit, “The Light Years,” declares “We were but stones, light made us stars.” Bringing light to the transmission electron microscope promises to transform our understanding of quantum materials, enabling both observation of light-mediated processes and control of optical emission. This presentation will describe our efforts to probe and control color centers in two promising materials: 1) hexagonal boron nitride (hBN) and 2) diamond nanoparticles. First, we investigate color centers in hBN, a wide bandgap semiconductor with bright, room temperature quantum emission. Through high resolution transmission electron imaging, we find that multiple emitters are located within a diffraction-limited spot, each contributing to the observed quantum emission. We also find four unique classes of quantum emitters with distinct spectral signatures, each of which is strain-tunable. Next, we investigate quantum emission from individual nanodiamonds. Within larger nanoparticles (>100nm), we observe heterogeneity of emission, including a red-shifting of the 738nm SiV emission across the nanoparticle, and increased intensity of the phonon sideband; the strongest emission is observed along grain boundaries. Within smaller nanoparticles (down to 1.7nm), we observe robust, single-defect emission. By combining atomic-scale imaging with AI, we help elucidate the atomic structure of individual quantum optical defects within sub-5nm nanodiamonds.