Sideband Cooling of a Trapped Ion in Strong Sideband Coupling Regime

TL;DR

This paper extends the theoretical understanding of sideband cooling of trapped ions into the strong coupling regime, showing that proper laser tuning can achieve cooling rates proportional to the linewidth, guiding experimental efforts.

Contribution

It generalizes previous models to include nonvanishing carrier transitions, demonstrating how to attain optimal cooling rates in the strong sideband coupling regime.

Findings

Cooling rate can be proportional to linewidth with proper laser tuning.

Theoretical predictions match exact solutions in the strong coupling regime.

Guides experimental realization of efficient sideband cooling.

Abstract

Conventional theoretical studies on the ground-state laser cooling of a trapped ion have mostly focused on the weak sideband coupling (WSC) regime, where the cooling rate is inverse proportional to the linewidth of the excited state. In a recent work~[New J. Phys. 23, 023018 (2021)], we proposed a theoretical framework to study the ground state cooling of a trapped ion in the strong sideband coupling (SSC) regime, under the assumption of a vanishing carrier transition. Here we extend this analysis to more general situations with nonvanishing carrier transitions, where we show that by properly tuning the coupling lasers a cooling rate proportional to the linewidth can be achieved. Our theoretical predictions closely agree with the corresponding exact solutions in the SSC regime, which provide an important theoretical guidance for sideband cooling experiments.