Focusing the electromagnetic field to 10−6λ for ultra-high enhancement of field-matter interaction

• Published in: Nature communications Vol. 12; no. 1; pp. 6389 - 7
• Main Authors: Chen, Xiang-Dong, Wang, En-Hui, Shan, Long-Kun, Feng, Ce, Zheng, Yu, Dong, Yang, Guo, Guang-Can, Sun, Fang-Wen
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 04.11.2021; Nature Publishing Group; Nature Portfolio
• Subjects: 639/624/1107/510; 639/624/399/1016; 639/925/927/1021; 639/925/927/481; Antennas; Coupling; Data processing; Diamonds; Electromagnetic fields; Electromagnetism; Evanescent waves; Humanities and Social Sciences; Information processing; Localization; Microwave photonics; multidisciplinary; Nanotechnology; Nanowires; Oscillations; Photonics; Quantum phenomena; Science; Science (multidisciplinary)
• ISSN: 2041-1723; 2041-1723
• DOI: 10.1038/s41467-021-26662-5

Focusing electromagnetic field to enhance the interaction with matter has been promoting researches and applications of nano electronics and photonics. Usually, the evanescent-wave coupling is adopted in various nano structures and materials to confine the electromagnetic field into a subwavelength space. Here, based on the direct coupling with confined electron oscillations in a nanowire, we demonstrate a tight localization of microwave field down to 10 −6 λ . A hybrid nanowire-bowtie antenna is further designed to focus the free-space microwave to this deep-subwavelength space. Detected by the nitrogen vacancy center in diamond, the field intensity and microwave-spin interaction strength are enhanced by 2.0 × 10 8 and 1.4 × 10 4 times, respectively. Such a high concentration of microwave field will further promote integrated quantum information processing, sensing and microwave photonics in a nanoscale system. Subwavelength focusing of electromagnetic fields often uses evanescent waves and nanostructures to aid confinement. Here, the authors localize a microwave field to 6 orders of magnitude smaller than the wavelength, by coupling to confined electron oscillations in a hybrid nanowire-bowtie antenna.