https://doi.org/10.1140/epjd/s10053-025-00960-9
Regular Article - Atomic Physics
Two-photon optical Ramsey–Doppler spectroscopy of positronium and muonium
Institute for Particle Physics and Astrophysics, ETH, 8093, Zurich, Switzerland
Received:
14
December
2024
Accepted:
17
January
2025
Published online:
3
March
2025
Positronium and muonium, as purely leptonic atoms without internal structure, provide ideal systems for high-precision tests of quantum electrodynamics (QED) and measurements of fundamental constants. However, the high velocities of these lightweight atoms complicate precision spectroscopy, particularly in the 1 S-2 S transition, due to transit time broadening and second-order Doppler shifts. To overcome these challenges, we propose a novel method combining two-photon Ramsey spectroscopy with a technique to correct the second-order Doppler shifts on an atom-by-atom basis. Additionally, this approach suppresses systematic effects of the AC Stark shift to a negligible level compared to the target precision. Simulations predict that for both positronium and muonium, this method could improve the measurement precision of the 1 S-2 S transition by more than two orders of magnitude compared to the current state of the art. This approach opens up new avenues for rigorous bound state QED tests and searches for physics beyond the standard model.
© The Author(s) 2025
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
