Two-Photon Optical Ramsey-Doppler Spectroscopy of Positronium and Muonium

TL;DR

This paper proposes a novel two-photon Ramsey spectroscopy method combined with Doppler shift correction to enhance the precision of 1S-2S transition measurements in positronium and muonium, enabling more accurate tests of QED.

Contribution

It introduces a new spectroscopic technique that significantly reduces Doppler and systematic effects in light leptonic atoms, improving measurement accuracy by over two orders of magnitude.

Findings

Simulations show potential for >100x precision improvement

Method effectively suppresses AC Stark shift systematic errors

Enables more rigorous tests of bound-state QED and new physics searches

Abstract

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 1S-2S 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 1S-2S 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.