Sympathetic cooling of a large ${}^{113}\mathrm{{Cd}}^{+}$ ion crystal with ${}^{40}\mathrm{{Ca}}^{+}$ in a linear Paul trap

TL;DR

This study demonstrates the sympathetic cooling and crystallization of large ${}^{113} ext{Cd}^+$ ion crystals using laser-cooled ${}^{40} ext{Ca}^+$ ions in a linear Paul trap, achieving ultracold temperatures and analyzing their properties.

Contribution

It presents the first large bicrystal of ${}^{113} ext{Cd}^+$ and ${}^{40} ext{Ca}^+$ ions, with detailed analysis of cooling factors and potential for improved frequency standards.

Findings

Crystallized up to 3.5×10^3 ${}^{40} ext{Ca}^+$ ions and 6.8×10^3 ${}^{113} ext{Cd}^+$ ions.

Achieved ${}^{113} ext{Cd}^+$ ion temperatures as low as 41 mK.

Studied effects of electrical parameters and ion ratios on sympathetic cooling.

Abstract

We have sympathetically cooled and crystallized ${}^{113}\mathrm{{Cd}}^{+}$ ions with laser-cooled ${}^{40}\mathrm{{Ca}}^{+}$ ions, and directly observed the complete large bicrystal structure in a linear Paul trap. The large two-component crystal contains up to $3.5\times10^3$ ${}^{40}\mathrm{{Ca}}^{+}$ ions and $6.8\times10^3$ ${}^{113}\mathrm{{Cd}}^{+}$ ions. The temperature of the crystallized ${}^{113}\mathrm{{Cd}}^{+}$ ions was measured to be as low as 41 mK with a large mass ratio. Moreover, we have studied several properties and structures of the ultracold sample. The factors affecting the sympathetic cooling effect were studied, including the electrical parameters and the number ratio between laser-cooled ions and sympathetically-cooled ions. The results of this paper enrich the experimental research of large two-component ion crystals, and the ultracold sample of ${}^{113}\mathrm{{Cd}}^{+}$ ions makes it possible to further improve the accuracy of the cadmium-ion microwave frequency standard.