Multilevel Electromagnetically Induced Transparency Cooling

TL;DR

This paper extends electromagnetically induced transparency (EIT) cooling to multilevel systems, providing a formalism to estimate cooling rates and enabling efficient near-ground-state cooling of complex ion systems.

Contribution

It introduces a new formalism for EIT cooling in multilevel systems, allowing accurate estimation of cooling rates without explicit motional simulations.

Findings

Developed a formalism for multilevel EIT cooling

Provided approximate estimates for cooling rates beyond weak coupling

Linked cooling rate to absorption spectrum for practical applications

Abstract

Electromagnetically Induced Transparency (EIT) cooling is a well-established method for preparing trapped ion systems in their motional ground state. However, isolating a three-level system, as required for EIT cooling, is often challenging or impractical. Nonetheless, multilevel systems can inherently host dark states. In this work, we extend the EIT cooling framework to such multilevel systems. We develop a formalism to accurately determine the cooling rate in the weak sideband coupling regime and provide an approximate estimate for cooling rates beyond this regime, without the need for explicit simulation of the motional degree of freedom. We clarify the connection between the cooling rate and the absorption spectrum, offering a pathway for efficient near-ground-state cooling of ions with complex electronic structures.