近日，加拿大卡尔加里大学A. J. Uribe Jimenez团队报道了反氢基态超精细分裂的4ppm测量。2026年5月27日出版的《自然》杂志发表了这项成果。

氢原子是量子理论的基础、演进与前沿的试金石。该原子的关键谱线已被测定至惊人的精度。

研究组聚焦于氢的反物质对应体——反氢原子，通过精密比较这两种原子体系，检验自然界的基本对称性（如电荷共轭、宇称反演和时间反演联合对称性，即CPT对称性）。近期对捕获反氢原子的1S–2S光谱测量已达到万亿分之一量级的相对精度。然而，对反质子内部结构敏感的超精细基态分裂，其测量精度仅为百万分之400（ppm）。

研究组报道了反氢原子基态超精细分裂能级a_1S的4 ppm测量结果，将现有最佳精度提升了两个数量级。通过对约24,000个反原子进行微波波谱学实验，研究组在1特斯拉磁场下测得该值，与氢原子的预期结果相符。在这一精度水平上，研究组的测量已能感知反质子的内部结构（其贡献约为 40 ppm），且接近现有理论分析的极限。所报道的进展得益于磁阱场控制、稳定与表征，反原子自旋态操控，以及反氢原子累积速率等方面的显著提升。

附：英文原文

Title: Four ppm measurement of the antihydrogen ground-state hyperfine splitting

Author: Akbari, R., de Araujo Azevedo, L. O., Baker, C. J., Bertsche, W., Bhatt, N. M., Bonomi, G., Capra, A., Carli, I., L. Cesar, C., Charlton, M., Cridland Mathad, A., Del Vincio, A., Duque Quiceno, D., Eriksson, S., Evans, A., Fajans, J., Friesen, T., Fujiwara, M. C., Golino, L. M., Gomes Gonalves, M. B., Hangst, J. S., Hayden, M. E., Heidari, P., Hodgkinson, D., Isaac, C. A., Jones, S. A., Jonsell, S., Madsen, N., Marshall, V. R., McKenna, J. T. K., Momose, T., Nauta, J., Oliveira, A. N., Powell, A., Rasmussen, C. ., Robertson-Brown, T., Robicheaux, F., Sacramento, R. L., Sarid, E., Schoonwater, J., Silveira, D. M., Singh, J., Smith, G., So, C., Stracka, S., Suh, J., Swadling, A. G., Tharp, T. D., Thompson, K. A., Thompson, R. I., Thorpe-Woods, E., Uribe Jimenez, A. J., Urioni, M., van de Werf, D. P., Wilson, S. G., Woosaree, P., Wurtele, J. S.

Issue&Volume: 2026-05-27

Abstract: The hydrogen atom is a touchstone for the foundations, evolution and frontiers of quantum theory1,2,3,4,5,6,7,8,9. Key spectral lines of this atom have been determined to remarkable precision10,11. Our research focuses on the study of antihydrogen, the antimatter counterpart of hydrogen. We test fundamental symmetries of nature (such as simultaneous charge conjugation, parity inversion, and time reversal or CPT symmetry) through precision comparisons of these atomic systems12. Recent 1S–2S spectroscopic measurements on trapped antihydrogen have achieved relative precisions of parts per trillion (refs.13,14). However, the ground-state hyperfine splitting, which is sensitive to the internal structure of the antiproton, has only been measured to 400parts per million (ppm). Here we report a 4ppm measurement of the antihydrogen ground-state hyperfine splitting energy a1S, advancing the state-of-the-art precision15 by two orders of magnitude. From microwave spectroscopy experiments with roughly 24,000 anti-atoms, we determine a1s/h=1420,404.8±1.1(stat.)±5.6(sys.)kHz in a 1-T magnetic field, consistent with expectations for hydrogen11. At this level, our measurement is sensitive to the internal structure of the antiproton, which contributes at about 40ppm and is approaching the limit of existing theoretical analyses16. The gains we report are the product of marked advances in magnetic trap field control, stabilization and characterization; anti-atom spin-state manipulation; and improved antihydrogen accumulation rate17.

DOI: 10.1038/s41586-026-10556-x

Source: https://www.nature.com/articles/s41586-026-10556-x