Photoionisation loading of large Sr+ ion clouds with ultrafast pulses

TL;DR

This paper demonstrates a novel ultrafast laser photoionisation method for loading large, pure Sr+ ion clouds in a linear Paul trap, offering advantages over traditional electron-bombardment techniques.

Contribution

It introduces a two-photon ultrafast pulse technique for efficient Sr+ ion loading, enabling larger and purer ion clouds at lower RF voltages.

Findings

Achieved trapping of up to 4x10^4 laser-cooled Sr+ ions.

Demonstrated advantages of photoionisation over electron-bombardment.

Enabled loading of pure Sr+ ion clouds at low RF voltages.

Abstract

This paper reports on photoionisation loading based on ultrafast pulses of singly-ionised strontium ions in a linear Paul trap. We take advantage of an autoionising resonance of Sr neutral atoms to form Sr+ by two-photon absorption of femtosecond pulses at a wavelength of 431nm. We compare this technique to electron-bombardment ionisation and observe several advantages of photoionisation. It actually allows the loading of a pure Sr+ ion cloud in a low radio-frequency voltage amplitude regime. In these conditions up to 4x10^4 laser-cooled Sr+ ions were trapped.