Coherence as an indicator to discern electromagnetically induced transparency and Autler-Townes splitting

TL;DR

This paper introduces an objective, AIC-based method to distinguish electromagnetically induced transparency from Autler-Townes splitting by analyzing coherence, providing a quantitative and noise-resilient transition criterion.

Contribution

It proposes a novel application of the Akaike's Information Criterion to differentiate EIT and ATS regimes through coherence analysis, improving accuracy over traditional width-based methods.

Findings

AIC test effectively distinguishes EIT and ATS regimes.

The transition point identified by the test aligns with theoretical predictions.

The method remains robust in noisy experimental conditions.

Abstract

Electromagnetically induced transparency (EIT) and Autler-Townes splitting (ATS) are generally characterized and distinguished by the width of the transparency created in the absorption profile of a weak probe in presence of a strong control field. This often leads to ambiguities, as both phenomena yield similar spectroscopic signature. However, an objective method based on Akaike's Information Criterion (AIC) test offers a quantitative way to discern the two regimes when applied on the probe absorption profile. The obtained transition value of control field strength was found to be higher than the value given by pole analysis of the corresponding off-diagonal density matrix element. By contrast, we apply the test on ground state coherence and the measured coherence quantifier, which yields a distinct transition point around the predicted value even in presence of noise. Our test accurately captures the transition between two regimes, indicating that a proper measure of coherence is essential for making such distinctions.