Jeon, Minseok Kim, Moohyuk Park, Nu-Ri Choi, Yeeun Lee, Junghyun Kim, Chulki Han, Sang-Wook Kang, Dongyeon Daniel Jeon, Seung-Woo Kim, Myung-Ki 2025-11-11T07:00:38Z 2025-11-11T07:00:38Z 2025-11-11 2025-12 1613-6810 https://pubs.kist.re.kr/handle/201004/153435 Solid-state quantum emitters, such as nitrogen-vacancy (NV) centers in diamond, offer a promising route toward scalable quantum technologies. However, their random spatial distribution and inherently broad dipole emission severely hinder high-purity single-photon extraction-particularly in low-numerical-aperture (NA) optical systems, which are essential for compact and scalable quantum photonic systems. Here, a defect-selective metalens integration approach is presented that allows precise and efficient single photon collection from individual NV centers, even under ultra-low-NA optical systems. Using an in situ transfer-printing process, high-purity silicon dioxide metalenses are stamped precisely and deterministically onto selected NV centers located 25 mu m below the diamond surface. This integration reshapes the broad dipolar emission of the targeted NV center into a tightly collimated, low-divergence beam, achieving a 40-fold enhancement in photon collection efficiency with an objective lens of NA = 0.07. Notably, emission is detected exclusively from metalens-coupled NV centers, effectively filtering out background noise from neighboring defects. Second-order correlation measurements yield g(()2())(0) = 0.04, unambiguously confirming the generation of high-purity single photons. This scalable, site-specific approach addresses key limitations in low-NA operation, opening the door to compact and fiber-integrated solid-state quantum photonics. English Wiley - V C H Verlag GmbbH & Co. High-Purity Single Photon Extraction from Diamond Nitrogen-Vacancy Centers in Low-Numerical-Aperture Optical Systems via Defect-Selective Metalens Printing Article 10.1002/smll.202510745 1 Small, v.21, no.50 Small 21 50 Y scie scopus 001605791700001 Chemistry, Multidisciplinary Chemistry, Physical Nanoscience & Nanotechnology Materials Science, Multidisciplinary Physics, Applied Physics, Condensed Matter Chemistry Science & Technology - Other Topics Materials Science Physics Article MAGNETIC-RESONANCE QUANTUM SPIN MAGNETOMETER REALIZATION diamond NV centers metalenses nanophotonics quantum interface single-photon emission transfer printing