2025-10-29 スイス連邦工科大学ローザンヌ校(EPFL)
Photograph of the photonic chip mounted on a custom holder. Credit: Yang et al 2025.
＜関連情報＞
- https://actu.epfl.ch/news/bridging-light-microwaves-and-electrons-for-precis/
- https://www.nature.com/articles/s41467-025-62808-5
マイクロ波、光、自由電子領域にわたる周波数計測の統一 Unifying frequency metrology across microwave, optical, and free-electron domains
Yujia Yang,Paolo Cattaneo,Arslan S. Raja,Bruce Weaver,Rui Ning Wang,Alexey Sapozhnik,Fabrizio Carbone,Thomas LaGrange & Tobias J. Kippenberg
Nature Communications Published:24 September 2025
DOI:https://doi.org/10.1038/s41467-025-62808-5
Abstract
Frequency metrology lies at the heart of precision measurement. Optical frequency combs provide a coherent link uniting the microwave and optical domains in the electromagnetic spectrum, with profound implications in timekeeping, sensing and spectroscopy, fundamental physics tests, exoplanet searches, and light detection and ranging. Here, we extend this frequency link to free electrons by coherent modulation of the electron phase by a continuous-wave laser locked to a fully stabilized optical frequency comb. Microwave frequency standards are transferred to the optical domain via the frequency comb, and are further imprinted in the electron spectrum by optically modulating the electron phase with a photonic chip-based microresonator. As a proof-of-concept demonstration, we apply this frequency link in the calibration of an electron spectrometer and verify its precision by measuring the absolute optical frequency. This approach achieves a 20-fold improvement in the accuracy of electron spectroscopy, relevant for investigating low-energy excitations in quantum materials, two-dimensional materials, nanophotonics, and quantum optics. Our work bridges frequency domains differed by a factor of ~ 1013 and carried by different physical objects, establishes a spectroscopic connection between electromagnetic waves and free-electron matter waves, and has direct ramifications in ultrahigh-precision electron spectroscopy.
