Trapping of electrons and $^{40}\textrm{Ca}^+$ ions in a dual-frequency Paul trap

TL;DR

This paper demonstrates a dual-frequency Paul trap capable of trapping electrons and calcium ions, analyzing its performance and potential for antihydrogen synthesis, with detailed experimental and simulation results.

Contribution

The paper introduces a dual-frequency Paul trap that can simultaneously trap electrons and calcium ions, providing insights into its operational characteristics and challenges.

Findings

Tens of electrons or ions can be trapped for up to ten milliseconds.

The number of trapped electrons decreases with increasing slow-frequency field amplitude.

The number of trapped ions is unaffected by the fast-frequency field amplitude.

Abstract

We demonstrate the operation of a dual-frequency Paul trap and characterize its performance by storing either electrons or calcium ions while applying two quadrupole fields simultaneously which oscillate at $\Omega_\textrm{fast} = 2\pi \times 1.6$ GHz and $\Omega_\textrm{slow} = 2\pi \times 2$ MHz. The particles are loaded and stored in the trap under various conditions followed by detection employing an electron multiplier tube. We find that tens of electrons or ions can be trapped for up to ten milliseconds and a small fraction remains trapped even after hundreds of milliseconds. During dual-frequency operation we find that while the number of trapped electrons rapidly decreases with increase of the $\Omega_\textrm{slow}$ field amplitude, the number of trapped ions shows no dependence on the $\Omega_\textrm{fast}$ field amplitude as supported by our extensive numerical simulations. We aim to use a similar trap for synthesising antihydrogen from antiprotons and positrons. Accordingly, we discuss open challenges such as the co-trapping of oppositely charged species and particle trap duration.