CPT tests with the antihydrogen molecular ion

TL;DR

This paper proposes high-precision spectroscopic methods on the antihydrogen molecular ion to perform CPT symmetry tests, potentially surpassing current hydrogen-antihydrogen comparison sensitivities.

Contribution

It introduces practical schemes for measuring the antihydrogen molecular ion in a Penning trap, enabling more sensitive CPT tests than previous methods.

Findings

Proposed measurement techniques for antihydrogen molecular ion.

Potential for surpassing current CPT test sensitivities.

Methods for creating and initializing the ion's quantum state.

Abstract

High precision radio-frequency, microwave and infrared spectroscopic measurements of the antihydrogen molecular ion $\bar{H}_{2}^{-}$ ($\bar{p}\bar{p}e^{+}$) compared with its normal matter counterpart provide direct tests of the CPT theorem. The sensitivity to a difference between the positron/antiproton and electron/proton mass ratios, and to a difference between the positron-antiproton and electron-proton hyperfine interactions, can exceed that obtained by comparing antihydrogen with hydrogen by several orders of magnitude. Practical schemes are outlined for measurements on a single $\bar{H}_{2}^{-}$ ion in a cryogenic Penning trap, that use non-destructive state identification by measuring the cyclotron frequency and bound-positron spin-flip frequency; and also for creating an $\bar{H}_{2}^{-}$ ion and initializing its quantum state.