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

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.