Experimental and theoretical investigation of a multi-mode cooling scheme using multiple EIT resonances

TL;DR

This paper introduces double-bright EIT cooling, a new method enabling efficient three-dimensional ground state cooling of trapped ions by using multiple resonances, with experimental validation and theoretical analysis.

Contribution

The paper presents the novel D-EIT cooling scheme that allows simultaneous multi-mode cooling using multiple EIT resonances, extending the capabilities of standard EIT cooling.

Findings

D-EIT cooling achieves efficient multi-mode ground state cooling.

Experimental results match theoretical models with some limitations.

Theoretical description improves with a time-dependent rate theory.

Abstract

We introduce and demonstrate double-bright electromagnetically induced transparency (D-EIT) cooling as a novel approach to EIT cooling. By involving an additional ground state, two bright states can be shifted individually into resonance for cooling of motional modes of frequencies that may be separated by more than the width of a single EIT cooling resonance. This allows three-dimensional ground state cooling of a $^{40}$Ca$^+$ ion trapped in a linear Paul trap with a single cooling pulse. Measured cooling rates and steady-state mean motional quantum numbers for this D-EIT cooling are compared with those of standard EIT cooling as well as concatenated standard EIT cooling pulses for multi-mode cooling. Experimental results are compared to full density matrix calculations. We observe a failure of the theoretical description within the Lamb-Dicke regime that can be overcome by a time-dependent rate theory. Limitations of the different cooling techniques and possible extensions to multi-ion crystals are discussed.