Cold neutral atoms via charge exchange from excited state positronium: a proposal

TL;DR

This paper proposes a novel method to produce cold neutral atoms through charge exchange with Rydberg positronium, enabling low-temperature experiments previously hindered by cooling challenges.

Contribution

It introduces a new scheme for generating cold neutral atoms from ions via charge exchange with positronium, facilitating experiments at ultra-low temperatures.

Findings

High charge exchange cross section enables efficient neutralization.

Neutrals can be produced at milli-Kelvin temperatures from cooled ions.

Potential for trapping and manipulating neutrals on an ion chip.

Abstract

We present a method for generating cold neutral atoms via charge exchange reactions between trapped ions and Rydberg positronium. The high charge exchange reaction cross section leads to efficient neutralisation of the ions and since the positronium-ion mass ratio is small, the neutrals do not gain appreciable kinetic energy in the process. When the original ions are cold the reaction produces neutrals that can be trapped or further manipulated with electromagnetic fields. Because a wide range of species can be targeted we envisage that our scheme may enable experiments at low temperature that have been hitherto intractable due to a lack of cooling methods. We present an estimate for achievable temperatures, neutral number and density in an experiment where the neutrals are formed at a milli-Kelvin temperature from either directly or sympathetically cooled ions confined on an ion chip. The neutrals may then be confined by their magnetic moment in a co-located magnetic minimum well also formed on the chip. We discuss general experimental requirements.