Coulomb crystallization of xenon highly charged ions in a laser-cooled Ca+ matrix

TL;DR

This study demonstrates the sympathetic cooling and Coulomb crystallization of highly charged xenon ions with laser-cooled calcium ions in a cryogenic trap, enabling advanced quantum control and precision measurements.

Contribution

It introduces a novel method for co-trapping and crystallizing xenon HCIs with Ca$^+$ ions, allowing detailed control and characterization of mixed-species Coulomb crystals.

Findings

Successful formation of mixed-species Coulomb crystals with xenon HCIs and Ca$^+$ ions

Measurement of xenon HCI charge states and lifetimes within the crystal

Observation of motional modes in xenon HCI-Ca$^+$ strings

Abstract

We report on the sympathetic cooling and Coulomb crystallization of xenon highly charged ions (HCIs) with laser-cooled Ca$^+$ ions. The HCIs are produced in a compact electron beam ion trap, then charge selected, decelerated, and finally injected into a cryogenic linear Paul trap. There, they are captured into $^{40}$Ca$^+$ Coulomb crystals, and co-crystallized within them, causing dark voids in their fluorescence images. Fine control over the number of trapped ions and HCIs allows us to realize mixed-species crystals with arbitrary ordering patterns. By investigating Xe$^{q+}$--Ca$^+$ strings, we confirm the HCI charge states, measure their lifetime and characterize the mixed-species motional modes. Our system effectively combines the established quantum control toolbox for Ca$^+$ with the rich set of atomic properties of Xe highly charged ions, providing a resourceful platform for optical frequency metrology, searches for signatures of new physics, and quantum information science.