Journal Article

Precision spectroscopy of the hyperfine components of the 1S–2S transition in antihydrogen

Grandemange, P., Jonsell, S., Kurchaninov, L., Evetts, N., Capra, A., Carruth, C., Eriksson, S., Olin, A., Khramov, A., Sarid, E., Isaac, C. A., Jones, J. M., Powell, A., Hodgkinson, D., Madsen, N., Wurtele, J. S., Hunter, E., Jones, S. A., Friesen, T., Hardy, W. N., Olchanski, K., Granum, P., Baker, C. J., Collister, R., Fajans, J., Gill, D. R., Tharp, T. D., Pusa, P., Silveira, D. M., Christensen, A., Cridland Mathad, A., Stutter, G., Charlton, M., Munich, J. J., van der Werf, D. P., Thompson, R. I., Shore, G. M., Bertsche, W., Hayden, M. E., Sacramento, R. L., Cesar, C. L., Momose, T., Mullan, P. S., Evans, A., Robicheaux, F., Rasmussen, C. Ø., Hangst, J. S., Fujiwara, M. C., So, C., Maxwell, D., Johnson, M. A., McKenna, J. T. K., Sameed, M., Menary, S., Peszka, J.

2025

Overview

The antimatter equivalent of atomic hydrogen—antihydrogen—is an outstanding testbed for precision studies of matter–antimatter symmetry. Here we report on the simultaneous observation of both accessible hyperfine components of the 1S–2S transition in trapped antihydrogen. We determine the 2S hyperfine splitting in antihydrogen and—by comparing our results with those obtained in hydrogen—constrain the charge–parity–time-reversal symmetry-violating coefficients in the standard model extension framework. Our experimental protocol allows the characterization of the relevant spectral lines in 1 day, representing a 70-fold improvement in the data-taking rate. We show that the spectroscopy is applicable to laser-cooled antihydrogen with important implications for future tests of fundamental symmetries. The ALPHA Collaboration reports measurements of the hyperfine components of the 1S–2S transition in trapped antihydrogen. They interpret the results as a test of the invariance of charge–parity–time-reversal symmetry.

• Publisher: Nature Publishing Group UK,Nature Publishing Group
• Subject: 639/766/36/1123 / 639/766/419/1131 / Antihydrogen / Antimatter / Atomic / Classical and Continuum Physics / Complex Systems / Condensed Matter Physics / Cooling / Equivalence / Hydrogen / Laser cooling / Lasers / Line spectra / Mathematical and Computational Physics / Molecular / Optical and Plasma Physics / Parity / Physics / Physics and Astronomy / Spectroscopy / Spectrum analysis / Symmetry / Theoretical