Electromagnetically-Induced-Transparency Cooling with a Tripod Structure in a Hyperfine Trapped Ion with Mixed-Species Crystals

TL;DR

This paper demonstrates a novel EIT cooling method for hyperfine trapped ions, enabling efficient cooling of multiple modes in mixed-species crystals, with potential broad applicability in quantum technologies.

Contribution

It introduces a new EIT cooling technique for ions with hyperfine structure by adding an extra laser frequency, and shows simultaneous cooling of multiple modes in mixed-species crystals.

Findings

Successful EIT cooling of 25Mg+ with an additional laser frequency.

Simultaneous cooling of all axial modes in mixed-species crystals.

Applicable to ions with non-zero nuclear spin.

Abstract

Cooling of atomic motion is a crucial tool for many branches of atomic physics, ranging from fundamental physics explorations to quantum information and sensing. For trapped ions, electromagnetically-induced-transparency (EIT) cooling has received attention for the relative speed, low laser power requirements, and broad cooling bandwidth of the technique. However, in applications where the ion used for cooling has hyperfine structure to enable long coherence times, it is difficult to find a closed three-level system in which to perform standard EIT cooling. Here, we demonstrate successful EIT cooling on 25Mg+ by the addition of an extra laser frequency; this method can be applied to any ion with non-zero nuclear spin. Furthermore, we demonstrate simultaneous EIT cooling of all axial modes in mixed-species crystals 9Be+ - 25Mg+ and 9Be+ - 25Mg+ - 9Be+ through the 25Mg+ ion.