Stimulated decay and formation of antihydrogen atoms

TL;DR

This paper explores methods to efficiently stimulate the decay of antihydrogen atoms from Rydberg states to the ground state, enhancing the production of ground-state antihydrogen for precision experiments.

Contribution

It proposes and assesses novel techniques using THz, microwave, and laser radiation to increase the ground state fraction of antihydrogen atoms.

Findings

Near-unity ground state fraction within microseconds achieved.

Stimulated radiative recombination improves initial state distribution.

Methods can significantly increase ground-state antihydrogen yield.

Abstract

Antihydrogen atoms are routinely formed at the Antiproton Decelerator at CERN in a wide range of Rydberg states. To perform precision measurements, experiments rely on ground state antimatter atoms which are currently obtained only after spontaneous decay. In order to enhance the number of atoms in ground state, we propose and assess the efficiency of different methods to stimulate their decay. First, we investigate the use of THz radiation to simultaneously couple all n-manifolds down to a low lying one with sufficiently fast spontaneous emission toward ground state. We further study a deexcitation scheme relying on state-mixing via microwave and/or THz light and a coupled (visible) deexcitation laser. We obtain close to unity ground state fractions within a few tens of microseconds for a population initiated in the n=30 manifold. Finally, we study how the production of antihydrogen atoms via stimulated radiative recombination can favourably change the initial distribution of states and improve the overall number of ground-state atoms when combined with the stimulated deexcitation proposed.