Quasi-analytical lineshape for the 1S-2S laser spectroscopy of antihydrogen and hydrogen

TL;DR

This paper introduces an analytical lineshape model for 1S-2S laser spectroscopy of hydrogen and antihydrogen, enabling faster and systematic studies of spectral data for high-precision fundamental physics tests.

Contribution

An analytical perturbation theory-based lineshape model that accounts for AC-Stark shift and ionization, improving analysis speed and systematic effect studies in hydrogen and antihydrogen spectroscopy.

Findings

Provides fast, reliable lineshape expressions for spectral analysis.

Facilitates studies of systematic effects in high-precision measurements.

Applicable to both beam and trapped atom experiments.

Abstract

The accuracy of high precision and fundamental measurements of atomic transition frequencies via laser spectroscopy depends upon fitting the spectral data with a lineshape. With atomic hydrogen and antihydrogen 1S-2S two-photon spectroscopy, computer intensive Monte-Carlo simulations have been used to compute the optical Bloch equations in order to match and interpret the experimental spectra. For the highest resolutions, one tries to minimize saturation effects going to regimes of low excitation probability, where perturbation theory can provide reliable results. Here we describe an analytical approach to the lineshape based on perturbation theory accounting for the AC-Stark shift and ionization. The expressions can be used for beam experiments or integrated over the magnetic field profile for a trapped sample. Theses lineshapes, providing fast results, allow for studies of many systematic effects that influence the accuracy of the determination of the central frequency. This development has relevance to hydrogen beam experiments and to trapped hydrogen and antihydrogen, as developed by the ALPHA collaboration at CERN, for tests of the CPT-symmetry and the highest accuracy measurement on antimatter.