Moon, Jong Sung Lee, Haneul Lee, Jin Hee Jeon, Woong Bae Lee, Dowon Lee, Junghyun Paik, Seoyoung Han, Sang-Wook Reuter, Rolf Denisenko, Andrej Wrachtrup, Joerg Lee, Sang-Yun Kim, Je-Hyung 2024-01-19T14:00:53Z 2024-01-19T14:00:53Z 2022-01-25 2021-09 2330-4022 https://pubs.kist.re.kr/handle/201004/116495 Point defects in crystals provide important building blocks for quantum applications. Since we optically address these defect qubits, having an efficient optical interface is a highly important aspect. However, conventional confocal fluorescence microscopy of high-refractive-index crystals suffers from limited photon collection efficiency and spatial resolution. Here, we demonstrate high-resolution, high-contrast imaging of defects in diamonds using microsphere-assisted confocal microscopy. A microsphere provides an excellent optical interface for point defects with a magnified virtual image that increases the spatial resolution up to lambda/5, as well as the optical signal-to-noise ratio by four times. These features enable individual optical addressing of single photons and single spins of multiple defects that are spatially unresolved in conventional confocal microscopy, with improved signal contrast. Combined with optical tweezers, this system also demonstrates the possibility of positioning or scanning the microspheres. The approach does not require any complicated fabrication or additional optical systems, but uses simple, off-the-shelf micro-optics. From these distinctive advantages of microspheres, our approach provides an efficient way to image and address closely spaced defects with much better resolution and sensitivity. English AMER CHEMICAL SOC High-Resolution, High-Contrast Optical Interface for Defect Qubits Article 10.1021/acsphotonics.1c00576 1 ACS PHOTONICS, v.8, no.9, pp.2642 - 2649 ACS PHOTONICS 8 9 2642 2649 N scie scopus 000697319600011 2-s2.0-85114498774 Nanoscience & Nanotechnology Materials Science, Multidisciplinary Optics Physics, Applied Physics, Condensed Matter Science & Technology - Other Topics Materials Science Optics Physics Article NITROGEN-VACANCY CENTERS SINGLE MICROSCOPY COHERENCE LIGHT SPINS COLLECTION point defects microsphere-assisted microscopy single photons optically detected magnetic resonance quantum sensing