Focusing the electromagnetic field to 10−6λ for ultra-high enhancement of field-matter interaction
Xiang-Dong Chen, Enhui Wang, Long‐Kun Shan, Ce Feng, Y. H. Zheng, Dong Yang, Guang‐Can Guo, Fang‐Wen Sun
Abstract
Abstract 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.