Increase of barium ion-trap lifetime via photodissociation

TL;DR

This study demonstrates that using a 225 nm UV laser to photodissociate reaction products significantly extends the lifetime of Ba$^+$ ions in a Paul trap, from hours to days, by recovering ions affected by background gas reactions.

Contribution

The paper introduces a method to increase ion trap lifetime by photodissociating reaction products with UV laser light, applicable to Ba$^+$ and potentially other ions.

Findings

Photodissociation at 225 nm recovers Ba$^+$ ions after reactions.

Trap lifetime increased from 6 hours to 2 days for a Coulomb crystal.

Photodissociation wavelengths for other ions are provided.

Abstract

The lifetime of Ba$^+$ ions confined in a Paul trap is found, under typical conditions, to be limited by chemical reactions with residual background gas. An integrated ion trap and time-of-flight mass spectrometer are used to analyze the reactions of the trapped Ba$^+$ ions with three common gases in an ultrahigh vacuum system (H$_2$, CO$_2$ and H$_2$O). It is found that the products of these reactions can all be photodissociated by a single ultraviolet laser at 225~nm, thereby allowing the recovery of the Ba$^+$ ions and leading to an increase of the effective trap lifetime. For a Coulomb crystal, the lifetime increased from roughly 6~hours to 2~days at room temperature. It is suggested that higher enhancement factors are possible in systems with stronger traps. In addition, photodissociation wavelengths for other common trapped ion systems are provided.