Efficient positronium laser excitation for antihydrogen production in a magnetic field

TL;DR

This paper proposes an efficient two-step laser excitation method for positronium atoms in a magnetic field to enhance antihydrogen production, accounting for Zeeman and Stark effects, and demonstrates feasible population transfer to high Rydberg states.

Contribution

It introduces a simplified formula for absorption probability under incoherent laser pulses and shows that 30% population transfer to high-n states is achievable with tailored lasers.

Findings

30% population transfer to high Rydberg states is feasible.

The physics of laser excitation in magnetic fields with Zeeman and Stark effects is analyzed.

A simple formula for absorption probability under incoherent pulses is derived.

Abstract

Antihydrogen production by charge exchange reaction between Positronium (Ps) atoms and antiprotons requires an efficient excitation of Ps atoms up to high-n levels (Rydberg levels). In this study it is assumed that a Ps cloud is produced within a relatively strong uniform magnetic field (1 Tesla) and with a relatively high temperature (100 K). Consequently, the structure of energy levels are deeply modified by Zeeman and motional Stark effects. A two-step laser light excitation, the first one from ground to n=3 and the second from this level to a Rydberg level, is proposed and the physics of the problem is discussed. We derive a simple formula giving the absorption probability with substantially incoherent laser pulses. A 30% population deposition in high-$n$ states can be reached with feasible lasers suitably tailored in power and spectral bandwidth.